Vehicular rearview mirror elements and assemblies incorporating these elements

ABSTRACT

The present invention relates to improved electro-optic rearview mirror elements and assemblies incorporating the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/477,312, filed Jun. 29, 2006, now U.S. Pat. No. 7,379,225, which is acontinuation of U.S. patent application Ser. No. 11/066,903, filed Feb.25, 2005, now U.S. Pat. No. 7,372,611, which claims priority to U.S.Provisional Application Ser. Nos. 60/614,150, filed Sep. 29, 2004,60/605,111, filed Aug. 27, 2004, and 60/548,472, filed Feb. 27, 2004,under 35 U.S.C. Sec. 119(e), the disclosures of which are incorporatedherein by reference in their entireties. This application is acontinuation-in-part of U.S. application Ser. No. 10/430,885, filed May6, 2003, now U.S. Pat. No. 7,324,261, and is also a continuation-in-partof U.S. application Ser. No. 10/260,741, filed Sep. 30, 2002, now U.S.Pat. No. 7,064,882, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND OF THE INVENTION

Electro-optic rearview mirror elements are becoming more common invehicular applications with regard to both inside and outside, bothdriver's and passenger's side, rearview mirrors. Typical electro-opticelements, when incorporated in vehicular rearview mirror assemblies,will have an effective field of view (as defined by relevant laws, codesand specifications) that is less than the area defined by the perimeterof the element itself. Primarily, the effective field of view islimited, at least in part, by the construction of the element itselfand, or, an associated bezel.

Various attempts have been made to provide an electro-optic elementhaving an effective field of view substantially equal to the areadefined by its perimeter. Assemblies incorporating these elements havealso been proposed.

What is needed is an improved electro-optic mirror element. Improvementsin assemblies incorporating these improved electro-optic mirror elementsare also needed.

SUMMARY OF THE INVENTION

At least one embodiment of the present invention provides improvedelectro-optic mirror elements. A related embodiment has an effectivefield of view area substantially equal to the field of view associatedwith an area defined by the perimeter of the element.

At least one embodiment of the present invention provides improvedassemblies incorporating electro-optic elements. A related embodimenthas an effective field of view area substantially equal to the area ofthe element itself as defined by its outer most perimeter.

Other advantages of the present invention will become apparent whilereading the detail description of the invention in light of the figuresand appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a controlled vehicle;

FIG. 2 a depicts an assembly incorporating an electro-optic element;

FIG. 2 b depicts an exploded view of an outside rearview mirror;

FIG. 3 depicts an inside rearview mirror assembly incorporating anelectro-optic element;

FIGS. 4 a-c depict first surface plan view, fourth surface plan view andsection view of an electro-optic element, respectively;

FIG. 4 d depicts a plan view of a fourth surface;

FIG. 4 e depicts a plan view of a second substrate;

FIG. 5 depicts an enlarged view of FIG. 4 c;

FIG. 6 depicts a graph of color related characteristics for variouselectro-optic element components;

FIGS. 7 a-n depicts various techniques for establishing externalelectrical connections to the second and third surface conductiveelectrodes;

FIGS. 8 a-n depict various electrical clips for establishing externalelectrical connections to the second and third surface conductiveelectrodes;

FIGS. 9 a-m depict various views of carrier/bezel assemblies for usewith electro-optic elements in a rearview mirror assembly; and

FIGS. 10 a-c depict various views of an electro-optic element/electricalcircuit board interconnection.

DETAIL DESCRIPTION OF THE INVENTION

Referring initially to FIG. 1, there is shown a controlled vehicle 105having a driver's side outside rearview mirror 110 a, a passenger's sideoutside rearview mirror 110 b and an inside rearview mirror 115. Detailsof these and other features will be described herein. Preferably, thecontrolled vehicle comprises an inside rearview mirror of unitmagnification. Unit magnification mirror, as used herein, means a planeor flat mirror with a reflective surface through which the angularheight and width of an image of an object is equal to the angular heightand width of the object when viewed directly at the same distance withthe exception for flaws that do not exceed normal manufacturingtolerances. A prismatic day-night adjustment rearview mirror wherein atleast one associated position provides unit magnification is consideredherein to be a unit magnification mirror. Preferably, the mirrorprovides a field of view with an included horizontal angle measured fromthe projected eye point of at least 20 degrees and a sufficient verticalangle to provide a view of a level road surface extending to the horizonbeginning at a point not greater than 61 m to the rear of the controlledvehicle when the controlled vehicle is occupied by a driver and fourpassengers or the designated occupant capacity, if less, based on anaverage occupant weight of 68 kg. It should be understood that the lineof sight may be partially obscured by seated occupants or by headrestraints. The location of the driver's eye reference points arepreferably in accordance with regulation or a nominal locationappropriate for any 95th percentile male driver. Preferably, thecontrolled vehicle comprises at least one outside mirror of unitmagnification. Preferably, the outside mirror provides a driver of acontrolled vehicle a view of a level road surface extending to thehorizon from a line, perpendicular to a longitudinal plane tangent tothe driver's side of the controlled vehicle at the widest point,extending 2.4 m out from the tangent plane 10.7 m behind the driver'seyes, with the seat in the rearmost position. It should be understoodthat the line of sight may be partially obscured by rear body or fendercontours of the controlled vehicle. Preferably, the locations of thedriver's eye reference points are in accordance with regulation or anominal location appropriate for any 95th percentile male driver.Preferably, the passenger's side mirror is not obscured by an unwipedportion of a corresponding windshield and is preferably adjustable bytilting in both horizontal and vertical directions from the driver'sseated position. In at least one embodiment, the controlled vehiclecomprises a convex mirror installed on the passenger's side. Preferably,the mirror is configured for adjustment by tilting in both horizontaland vertical directions. Preferable, each outside mirror comprises notless than 126 cm of reflective surface and is located so as to providethe driver a view to the rear along an associated side of the controlledvehicle. Preferably, the average reflectance of any mirror, asdetermined in accordance with SAE Recommended Practice J964, OCT84, isat least 35 percent (40% for many European Countries). In embodimentswhere the mirror element is capable of multiple reflectance levels, suchas with electro-optic mirror elements in accordance with the presentinvention, the minimum reflectance level in the day mode shall be atleast 35 (40 when for European use) percent and the minimum reflectancelevel in the night mode shall be at least 4 percent.

With further reference to FIG. 1, the controlled vehicle 105 maycomprise a variety of exterior lights, such as, headlight assemblies 120a, 120 b, foul conditions lights 130 a, 130 b, front turn signalindicators 135 a, 135 b, taillight assembly 125 a, 125 b, rear turnsignal indicators 126 a, 126 b, rear emergency flashers 127 a, 127 b,backup lights 140 a, 140 b and center high mounted stop light (CHMSL)145.

As described in detail herein, the controlled vehicle may comprise atleast one control system incorporating various components that provideshared function with other vehicle equipment. An example of one controlsystem described herein integrates various components associated withautomatic control of the reflectivity of at least one rearview mirrorelement and automatic control of at least one exterior light. Suchsystems may comprise at least one image sensor within a rearview mirror,an A-pillar, a B-pillar, a C-pillar, a CHMSL or elsewhere within or uponthe controlled vehicle. Images acquired, or portions thereof, maybe usedfor automatic vehicle equipment control. The images, or portionsthereof, may alternatively, or additionally, be displayed on one or moredisplays. At least one display may be covertly positioned behind atransflective, or at least partially transmissive, electro-opticelement. A common controller may be configured to generate at least onemirror element drive signal and at least one other equipment controlsignal.

Turning now to FIGS. 2 a and 2 b, various components of an outsiderearview mirror assembly 210 a, 210 b are depicted. As described indetail herein, an electro-optic mirror element may comprise a firstsubstrate 220 a, 220 b secured in a spaced apart relationship with asecond substrate 225 via a primary seal 230 to form a chamber therebetween. At least a portion of the primary seal is left void to form atleast one chamber fill port 235. An electro-optic medium is enclosed inthe chamber and the fill port(s) are sealingly closed via a plugmaterial 240. Preferably, the plug material is a UV curable epoxy oracrylic material. Also shown is a spectral filter material 245 a, 245 blocated near the periphery of the element. Electrical clips 250, 255 arepreferably secured to the element, respectively, via first adhesivematerial 251, 252. The element is secured to a carrier plate 260 viasecond adhesive material 265. Electrical connections from the outsiderearview mirror to other components of the controlled vehicle arepreferably made via a connector 270. The carrier is attached to anassociated housing mount 276 via a positioner 280. Preferably, thehousing mount is engaged with a housing 275 a, 275 b and secured via atleast one fastener 276 a. Preferably the housing mount comprises aswivel portion configured to engage a swivel mount 277 a, 277 b. Theswivel mount is preferably configured to engage a vehicle mount 278 viaat least one fastener 278 a. Additional details of these components,additional components, their interconnections and operation is providedherein.

With further reference to FIG. 2 a, the outside rearview mirror assembly210 a is oriented such that a view of the first substrate 220 a is shownwith the spectral filter material 245 a positioned between the viewerand the primary seal material (not shown). A blind spot indicator 285, akeyhole illuminator 290, a puddle light 292, a turn signal 294, a photosensor 296, anyone thereof, a subcombination thereof or a combinationthereof may be incorporated within the rearview mirror assembly suchthat they are positioned behind the element with respect to the viewer.Preferably, the devices 285, 290, 292, 294, 296 are configured incombination with the mirror element to be at least partially covert asdiscussed in detail within various references incorporated by referenceherein. Additional details of these components, additional components,their interconnections and operation are provided herein.

Turning now to FIG. 3, there is shown an inside rearview mirror assembly310 as viewed looking at the first substrate 320 with a spectral filtermaterial 345 positioned between the viewer and a primary seal material(not shown). The mirror element is shown to be positioned within amovable housing 375 and combined with a stationary housing 377 on amounting structure 381. A first indicator 386, a second indicator 387,operator interfaces 391 and a first photo sensor 396 are positioned in achin portion of the movable housing. A first information display 388, asecond information display 389 and a second photo sensor 397 areincorporated within the assembly such that they are behind the elementwith respect to the viewer. As described with regard to the outsiderearview mirror assembly, it is preferable to have devices 388, 389, 397at least partially covert. For example, a “window” may be formed in theassociated mirror element third and, or, fourth surface coatings andconfigured to provide a layer of a platinum group metal (PGM) (i.e.iridium, osmium, palladium, platinum, rhodium, and ruthenium) only onthe third surface. Thereby, light rays impinging upon the associated“covert” photo sensor “glare” will first pass through the first surfacestack, if any, the first substrate, the second surface stack, theelectro-optic medium, the platinum group metal and, finally, the secondsubstrate. The platinum group metal functions to impart continuity inthe third surface conductive electrode, thereby, reducing electro-opticmedium coloring variations associated with the window.

Turning now to FIGS. 4 a-4 e and 5, a discussion of additional featuresof the present invention is provided. FIG. 4 a depicts a rearview mirrorelement 400 a viewed from the first substrate 402 a with a spectralfilter material 496 a positioned between the viewer and a primary sealmaterial 478 a. A first separation area 440 a is provided tosubstantially electrically insulate a first conductive portion 408 afrom a second conductive portion 430 a. A perimeter material 460 a isapplied to the edge of the element. FIG. 4 b depicts a rearview mirrorelement 400 b viewed from the second substrate 412 b with a primary sealmaterial 478 b positioned between the viewer and a spectral filtermaterial 496 b. A second separation area 486 b is provided tosubstantially electrically insulate a third conductive portion 418 bfrom a fourth conductive portion 487 b. A perimeter material 460 b isapplied to the edge of the element. FIG. 4 c depicts a rearview mirrorelement 400 c viewed from a section line FIG. 4 c-FIG. 4 c of either theelement of FIG. 4 a or 4 b. A first substrate 402 c is shown to besecured in a spaced apart relation via a primary seal material 478 cwith a second substrate 412 c. A spectral filter material 496 c ispositioned between a viewer and the primary seal material 478 c. Firstand second electrical clips 463 c, 484 c, respectively, are provided tofacilitate electrical connection to the element. A perimeter material460 c is applied to the edge of the element. It should be understoodthat the primary seal material may be applied by means commonly used inthe LCD industry such as by silk-screening or dispensing. U.S. Pat. No.4,094,058, to Yasutake et al., the disclosure of which is incorporatedin its entirety herein by reference, describes applicable methods. Usingthese techniques the primary seal material may be applied to anindividually cut to shape substrate or it can be applied as multipleprimary seal shapes on a large substrate. The large substrate withmultiple primary seals applied may then be laminated to another largesubstrate and the individual mirror shapes can be cut out of thelaminate after at least partially curing the primary seal material. Thismultiple processing technique is a commonly used method formanufacturing LCD's and is sometimes referred to as an array process.Electro-optic devices can be made using a similar process. All coatingssuch as the transparent conductors, reflectors, spectral filters and inthe case of solid state electro-optic devices the electro-optic layer orlayers may be applied to a large substrate and patterned if necessary.The coatings can be patterned using a number of techniques such as byapplying the coatings through a mask, by selectively applying apatterned soluble layer under the coating and removing it and thecoating on top of it after coating application, laser ablation oretching. These patterns can contain registration marks or targets thatcan be used to accurately align or position the substrates throughoutthe manufacturing process. This is usually done optically for instancewith a vision system using pattern recognition technology. Theregistration marks or targets may also be applied to the glass directlysuch as by sand blasting, laser or diamond scribing if desired. Spacingmedia for controlling the spacing between the laminated substrates maybe placed into the primary seal material or applied to a substrate priorto lamination. The spacing media or means may be applied to areas of thelaminate that will be cut away from the finished singulated mirrorassemblies. The laminated arrays can be cut to shape before or afterfilling with electro-optic material and plugging the fill port if thedevices are solution phase electro-optic mirror elements.

FIG. 4 d depicts a plan view of a second substrate 412 d comprising astack of materials on a third, fourth or both third and fourth surfaces.In at least one embodiment, at least a portion 420 d 1 of a stack ofmaterials, or at least the substantially opaque layers of a stack ofmaterials, are removed, or masked, beneath the primary seal material. Atleast a portion 420 d 2 of at least a layer of the stack of materialsextends substantially to the outer edge of the substrate or extends toan area to facilitate electrical contact between the third surface stackand an element drive circuit (not shown). Related embodiments providefor inspection of the seal and, or, plug viewing and, or, plug curingthe rear of the element subsequent to element assembly. In at least oneembodiment, at least a portion of an outer edge 420 d 1 of a stack ofmaterials 420 d is located between an outer edge 478 d 1 and an inneredge 478 d 2 of a primary seal material 478 d. In at least oneembodiment, the portion 420 d 1 of a stack of materials, or at least thesubstantially opaque layers of a stack of materials, are removed, ormasked, beneath the primary seal material between approximately 2 mm andapproximately 8 mm wide, preferably approximately 5 mm wide. At least aportion 420 d 2 of at least a layer of the stack of materials extendssubstantially to the outer edge of the substrate or extends to an areato facilitate electrical contact between the third surface stack and anelement drive circuit (not shown) between approximately 0.5 mm andapproximately 5 mm wide, preferably approximately 1 mm. It should beunderstood that any of the first, second, third and fourth surfacelayers or stacks of materials may be as disclosed herein or within thereferences incorporated elsewhere herein by reference.

FIG. 4 e depicts a plan view of a second substrate 412 e comprising athird surface stack of materials. In at least one embodiment, at least aportion of an outer edge 420 e 1 of a third surface stack of materials420 e is located between an outer edge 478 e 1 and an inner edge 478 e 2of a primary seal material 478 e. In at least one related embodiment, aconductive tab portion 482 e extends from an edge of the secondsubstrate inboard of an outer edge 478 e 1 of a primary seal material478 e. In at least one related embodiment, a conductive tab portion 482e 1 overlaps with at least a portion of a third surface stack ofmaterials beneath a primary seal material 478 e. In at least oneembodiment, a substantially transparent conductive layer (not shownindividually), such as a conductive metal oxide, of a third surfacestack of materials extends beyond an outer edge 420 e 1 of a remainderof the third surface stack and is in electrical communication with aconductive tab portion as depicted in FIG. 7 k. It should be understoodthat the conductive tab may be deposited along any of the substrateperipheral areas as shown in FIGS. 7 d-7 n. In at least one embodiment,a conductive tab portion comprises chrome. It should be understood thatthe conductive tab portion improves conductivity over the conductiveelectrode; as long as a conductive electrode layer is provided withsufficient conductivity, the conductive tab portion is optional. In atleast one embodiment, the conductive electrode layer imparts the desiredcolor specific characteristics of the corresponding reflected light raysin addition to providing the desired conductivity. Therefore, when theconductive electrode is omitted, color characteristics are controlledvia the underlayer material specifications. It should be understood thatany of the first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

FIG. 5 depicts rearview mirror element 500 which is an enlarged view ofthe element depicted in FIG. 4 c to provide greater detail. Element 500comprises a first substrate 502 having a first surface 504 and a secondsurface 506. A first conductive electrode portion 508 and a secondconductive electrode portion 530 applied to the second surface 506 aresubstantially electrically insulated from one another via a firstseparation area 540. As can be seen, in at least one embodiment theseparation area is located such that the spectral filter material 596and a corresponding adhesion promotion material 593 are alsosubstantially electrically insulated to define first and second spectralfilter material portions 524, 536, respectively, and first and secondadhesion promotion material portions 527, 539, respectively. A portionof the first separation area 540, 440 a, 440 b, 440 c is shown to beextending parallel within a portion of the primary seal material 578located near the center thereof. It should be understood that thisportion of the separation area 540 may lie such that a viewer would notreadily perceive a line within the spectral filter material; forexample, a portion of the separation area may be substantially alignedwith an inboard edge 597 of spectral filter material 596. It should beunderstood that when any portion of the separation area 540 is locatedinboard of the primary seal material, as is described in more detailelsewhere herein, a discontinuity in the electro-optic material coloringand, or, clearing may be observed. This operational characteristic maybe manipulated to derive a subjectively visually appealing element.

With further reference to FIG. 5, the element 500 is depicted tocomprise a second substrate 512 having a third surface 515 and a fourthsurface 514. It should be noted that the first substrate may be largerthan the second substrate to create an offset along at least a portionof the perimeter of the mirror. Third and fourth conductive electrodeportions 518, 587, respectively, are shown proximate the third surface515 substantially electrically insulated via second separation area 586.A portion of the second separation area 586, 486 a, 486 b, 486 c isshown to be extending parallel within a portion of the primary sealmaterial 578 located near the center thereof. It should be understoodthat this portion of the separation area 586 may lie such that a viewerwould not readily perceive a line within the spectral filter material;for example, a portion of the separation area may be substantiallyaligned with an inboard edge 597 of spectral filter material 596. Asfurther shown in FIG. 5, a reflective material 520 may be appliedbetween an optional overcoat material 522 and the third conductiveelectrode portion 518. It should be understood that any of the materialsas disclosed in commonly assigned U.S. Pat. Nos. 6,111,684, 6,166,848,6,356,376, 6,441,943, Ser. No. 10/115,860 U.S. Pat. Nos. 5,825,527,6,111,683, 6,193,378, Ser. Nos. 09/602,919, 10/260,741 and 10/430,885,the disclosures of which are incorporated herein by reference, may beemployed to define a unitary surface coating, such as a hydrophiliccoating on a first surface, or a composite stack of coatings, such asconductive electrode material, spectral filter material, adhesionpromotion material, reflective material, overcoat material applied tothe first, second, third and fourth surfaces. It should be additionallyunderstood that a hydrophobic coating, such as, a fluorinated alkylsaline or polymer, a silicone containing coating or a specially texturedsurface may be applied to the first surface. Either a hydrophilic orhydrophobic coating will alter the contact angle of moisture impingingupon the first surface relative to glass with no such coating and willenhance rear vision when moisture is present. It should be understoodthat both third surface and fourth surface reflector embodiments arewithin the scope of the present invention. In at least one embodiment,the materials applied to the third surface and, or, fourth surface areconfigured to provide a partially reflective/partially transmissivecharacteristic for at least a portion of the corresponding surfacestack. In at least one embodiment, the materials applied to the thirdsurface are integrated to provide a combination reflector/conductiveelectrode. It should be understood that additional “third surface”materials may extend outboard of the primary seal, in which case, itshould be understood that the corresponding separation area extendthrough the additional materials. Having at least a portion of theprimary seal visible from the fourth surface, as depicted in FIG. 4 dfor example, facilitates inspection and UV curing of plug material. Inat least one embodiment, at least a portion of a stack of materials 420d, or at least the substantially opaque layers of a stack of materials,are removed, or masked, beneath the primary seal material to provide forinspection of at least 25% of the primary seal width around at least aportion of the perimeter. It is more preferred to provide for inspectionof 50% of the primary seal width around at least a portion of theperimeter. It is most preferred to provide for inspection of at least75% of the primary seal width around at least a portion of theperimeter. Various embodiments of the present invention will incorporateportions of a particular surface having a coating or stack of coatingsdifferent from other portions; for example, a “window” in front of alight source, information display, a photo sensor, or a combinationthereof may be formed to selectively transmit a particular band of lightray wavelengths or bands of light ray wavelengths as described in manyof the references incorporated herein.

With further reference to FIGS. 4 a-4 b and 5, the first separation area540 cooperates with a portion of the primary seal material 575 to definethe second conductive electrode portion 530, the second spectral filtermaterial portion 536 and the second adhesion promotion material portion539 substantially electrically insulated from the first conductiveelectrode portion 508, the first spectral filter material portion 524and first adhesion promotion material portion 527. This configurationallows for placement of an electrically conductive material 548 suchthat the first electrical clip 563 is in electrical communication withthe third conductive electrode portion 518, the reflective material 520,the optional overcoat 522 and the electro-optic medium 510. It should beapparent, particularly in embodiments wherein the electricallyconductive material 548 is applied to the element prior to placement ofthe first electrical clip 569, that electrically conductive material mayat least partially separate the interfaces 557, 566, 572, 575.Preferably, the material, or composition of materials, forming the thirdconductive electrode portion 518, the first electrical clip 563 and theelectrically conductive material 548 are chosen to promote durableelectrical communication between the clip and the materials leading tothe electro-optic medium. The second separation area 586 cooperates witha portion of the primary seal material 575 to define the fourthconductive electrode portion 587 substantially electrically insulatedfrom the third conductive electrode portion 518, the reflective layer520, the optional overcoat material 522 and the electro-optic medium510. This configuration allows for placement of an electricallyconductive material 590 such that the second electrical clip 584 is inelectrical communication with the first adhesion promotion materialportion 527, the first spectral filter material portion 524, the firstconductive electrode portion 508 and the electro-optic medium 510. Itshould be apparent, particularly in embodiments wherein the electricallyconductive material 590 is applied to the element prior to placement ofthe first electrical clip 584, that electrically conductive material mayat least partially separate the interfaces 585, 588, 589. Preferably,the material, or composition of materials, forming the first conductiveelectrode portion 508, the first electrical clip 584, the adhesionpromotion material 593, the spectral filter material 596 and theelectrically conductive material 590 are chosen to promote durableelectrical communication between the clip and the materials leading tothe electro-optic medium.

Preferably, the perimeter material 560 is selected such that theresulting visible edge surface is visually appealing and such that goodadhesion is obtained at interfaces 533, 545 554. It should be understoodthat at least a portion of the first substrate 502 in the areasproximate the first corner 503, the edge 505, the second corner 507 andcombinations thereof may be treated to smooth protrusions anddepressions noticeable to a viewer. It is within the scope of thepresent invention to treat at least a portion of a surface, a corner, anedge or a combination thereof to define “beveled,” “rounded,” orcombinations thereof. Commonly assigned U.S. patent application Ser.Nos. 10/260,741 and 10/430,885 describe various mechanisms for carryingout the edge treatment. The corresponding treatment improves the visualappearance and durability of the element.

Turning to FIG. 6 and Tables 1-4a, the color rendered as a result ofhaving an indium-tin-oxide conductive electrode between the secondsurface of the first substrate and a spectral filter material, or ring,is described. In the example mirror element description containedherein, the reflectivity associated with the spectral filter materialwith respect to that of the third surface reflector results, in at leastone embodiment, in a more blue hue for the spectral filter material whenthe electro-optic medium is in a “clear” sate. As depicted in the Tablescontained herein, the b* of the reflector is higher than the b* of thespectral filter material. When there is mismatch between the hue of themain reflector and spectral filter material it is often desirable tohave a spectral filter material with a lower b* value than the mainreflective area. Many outside mirrors are designed to have a bluish huein the main reflective area. As described in at least one embodimentherein, use of aluminum in combination with, or in lieu of, chrome forthe spectral filter material provides additional color renderingoptions. Other options, or embodiments, are depicted with provide abetter match between the ring and the mirror viewing area. In theseother cases the spectral filter or ring has virtually identicalreflectance and color allowing a seamless match between the viewing areaand the ring.

Table 1 summarizes various color characteristics, namely, Y specularincluded (A10); a*; b*; C* and Y specular excluded, for seven uniquelyconfigured spectral filter materials, second surface conductiveelectrode and related materials.

Tables 1a through 1d contain variations for the spectral filtermaterials. The reflectance is in CIE-D65. Individual layers thicknessesare in nanometers. Table 1a shows the effect of chrome thickness on thestack Glass/ITO/Cr/Ru/Rh. The reflectance of the stack increases as thethickness of the chrome is thinned. In this example the refractive indexof the chrome is n=3.4559 and k=3.9808. Where n represents the realportion and k represents the imaginary portion of a complex number. Therefractive index of the chrome in part defines the reflectivity of thestack and will be discussed in more detail later. Also as the chrome isthinned the reflected a* values increase leading to a better match forthe ring material.

In at least one embodiment, the reflectivity of the spectral filter isincreased by putting Rhodium next to the first chrome layer instead ofRuthenium. Table 1b shows the effect of chrome thickness on thereflectance and color of the ring as the chrome thickness is changed.Again, like the previous example, the reflectance increases as thechrome layer is thinned. This example is preferred when the reflectanceof the center of the mirror reflectance is relatively high.

Typical production mirror properties are shown below:

Full Mirror Reference Color Reflectance a* b* Typical Outside Mirror56.3 −2.2 2.4 Typical Inside Mirror 85.0 −3.0 5.0

TABLE 1a alternate stacks - chrome thickness with ruthenium Run # ITO CrRu Rh Cr Ru Rh CIE-D65 R a* b* 1 118 60 20 3.5 45.5 −6.1 −3.1 2 118 2020 3.5 47.5 −4.9 −2.8 3 118 10 20 3.5 50.24 −4.3 −2.3 4 118 5 20 3.551.16 −4.3 −2.1 5 118 2.5 20 3.5 51.17 −4.3 −1.9

TABLE 1b alternate stacks - chrome thickness with rhodium/ruthenium Run# ITO Cr Ru Rh Cr Ru Rh CIE-D65 R a* b* 17 118 0 5 30 59.82 −3.3 −0.1418 118 2.5 5 30 57.36 −3.2 −0.6 19 118 5 5 30 54.9 −3.3 −1.1 20 118 7.55 30 52.64 −3.6 −1.6 21 118 10 5 30 50.66 −3.9 −2.2 22 118 12.5 5 3049.02 −4.3 −2.6

Table 1c depicts the effect of Ruthenium thickness when a thin Rhodiumlayer is used next to a thin chrome layer. A particular benefit isattained when the Ruthenium is approximately 20 nm. The minimumrequirement of Ruthenium will vary with Rhodium thickness, the thinchrome thickness and the target reflectivity value.

TABLE 1c alternate stacks - varying ruthenium behind rhodium Run # ITOCr Ru Rh Cr Ru Rh CIE-D65 R a* b* 11 118 5 2.5 0 19.63 −8.5 −3.4 12 1185 2.5 10 44.46 −4.7 −2.8 13 118 5 2.5 20 52.9 −3.7 −1.6 14 118 5 2.5 3053.97 −3.6 −1.3 15 118 5 2.5 40 53.4 −3.9 −1.6

Table 1d depicts the how the reflectance will change with Rhodiumthickness at a fixed chrome and Ruthenium thickness. The intensity ofthe reflectance increases with increasing Rhodium thickness and thereflected a* increases. The increase in the reflected a* may beexploited to help improve the color match between the center of glassand the ring. The change in reflectance with changing Rhodium thicknesswill differ depending on the thickness of the chrome layer between theRhodium and the ITO. The thicker the chrome layer, the more the Rhodiumreflectance will be dampened. Also in Table 1d are alternate metalsbetween a thin and thick chrome layer. Palladium, Iridium, Cadmium andPlatinum are shown. The reflectance versus metal thickness is shownalong with the effect of changing the thin chrome base layer thickness.

TABLE 1d alternate stacks - varying rhodium thickness Run # ITO Cr Ru RhCr Ru Rh CIE-D65 R a* b* 118 5 0 30 52.59 −4 −1.6 14 118 5 2.5 30 53.97−3.6 −1.3 16 118 5 5 30 54.9 −3.3 −1.1 19 118 5 7.5 30 55.5 −3.1 −0.9Glass 1.2 mm 1.2 mm 1.2 mm 1.2 mm 1.2 mm 1.2 mm ITO 120 120 120 120 120120 IRIDIUM 3 6 9 12 15 18 CR 40 40 40 40 40 40 R (cap Y) 50.5 52.8 54.355.4 56.0 56.4 ITO 120 120 120 120 120 120 Chrome 1 2 4 6 8 10 IRIDIUM15 15 15 15 15 15 CR 40 40 40 40 40 40 R (cap Y) 55.3 54.5 53.3 52.251.4 50.8 ITO 120 120 120 120 120 120 Palladium 3 6 9 12 15 18 CR 40 4040 40 40 40 R (cap Y) 50.9 53.6 55.6 57.0 58.0 58.7 ITO 120 120 120 120120 120 Chrome 1 2 4 6 8 10 Palladium 15 15 15 15 15 15 CR 40 40 40 4040 40 R (cap Y) 56.5 55.2 53.0 51.5 50.4 49.6 ITO 120 120 120 120 120120 Platinum 3 6 9 12 15 18 CR 40 40 40 40 40 40 R (cap Y) 49.7 51.352.3 52.9 53.1 53.2 ITO 120 120 120 120 120 120 Chrome 1 2 4 6 8 10Platinum 15 15 15 15 15 15 CR 40 40 40 40 40 40 R (cap Y) 52.3 51.6 50.549.7 49.2 48.9 ITO 120 120 120 120 120 120 Cadmium 3 6 9 12 15 18 CR 4040 40 40 40 40 R (cap Y) 52.3 56.5 59.9 62.5 64.6 66.1 ITO 120 120 120120 120 120 Chrome 1 2 4 6 8 10 Cadmium 15 15 15 15 15 15 CR 40 40 40 4040 40 R (cap Y) 62.2 60.1 56.6 54.0 52.0 50.7

Different metals or mixtures of metals may be used next to the thinchrome layer. The thin chrome layer may be considered optional, it isused when an adhesion promoter layer is desired. Alternate adhesionpromoting metals or materials may fulfill a comparable function. Thedifferent metals are selected to alter the reflectance, either higher orlower, depending on the match desired with respect to the center of theviewing area. The metal can have another benefit, that of altering thecolor or hue of the ring area. The presence of the ITO or otherdielectric layer under the metals tends to move the color to a morenegative b* direction. The use of a “red” high reflectance metal such ascopper may both enhance reflectivity while simultaneously facilitating acolor match to the viewing area. Table 1e shows the effect of a thincopper layer placed between two chrome layers. The reflectance issubstantially increased while simultaneously making the ring color moreneutral. A copper gold alloy similar properties.

TABLE 1e Color and reflectance effects of copper addition to stack ITO114 114 Chrome 1 1 Copper 0 15 Chrome 40 40 R 47.3 56.2 a* −5.2 −0.7 b*−3.5 2.3

Suitable metals which will result in increased reflectance includecadmium, cobalt, copper, palladium, silver, gold, aluminum and iridiumor other high reflectance metals, their alloys and/or mixtures ofmetals.

TABLE 1 D65-2 Macbeth D65-2 Color Eye 7000 Reflectance A10 (specularincluded) Y Trial Y a* b* C* specular excluded 1 856csito 11.665 2.088−5.491 5.874 0.01 2 cswchr 38.312 −3.477 4.183 5.439 0.133 3 cswchral61.366 −3.108 6.965 7.627 0.186 4 halfchral 61.679 −4.484 12.279 13.0720.376 5 halfchr 41 −5.929 12.809 14.114 0.073 6 Tec15Chr 23.76 0.9848.603 8.659 1.322 7 Tec 15 11.284 −3.363 0.442 3.392 0.162 1 - Glass/856Ang. Al203/Half wave (Optical thickness) ITO 2 - 1 plus opaque chromelayer 3 - 1 plus approx 30 Ang. Chrome/250 Ang. Aluminum 4 - Glass/Halfwave ITO/30 Ang. Chrome/250 Ang. Aluminum 5 - Glass/Half wave ITO/OpaqueChrome layer 6 - Glass/Tec15/Opaque chrome 7 - Tec 15

Table 2 summarizes various color characteristics, namely, a*; b*; C* andY specular included (A10) for the combinations of variousindium-tin-oxide second surface conductive electrodes positioned betweena first substrate and a substantially paque chrome spectral filtermaterial. The data contained in this table depicts the ability tocontrol the resulting b* value by varying the ITO thickness fromapproximately 65% to approximately 100% of a ½ wave thickness. Specificthicknesses anticipated to obtain a given color may vary somewhat basedon deposition parameters that affect the optical constants. The color ofa particular stack may vary, to some degree, based on choice of processparameters, as well as, process fluctuations that result in small, but,sometimes significant shifts in the optical constants of the materialsused. For example, the half wave optical thickness of ITO willcorrespond to a lesser physical thickness if the physical density of thecoating is increased and an increase absorption in the ITO coating woulddecrease the reflectivity of a second surface ITO plus chrome stack.This does not negate the fact that over the range of optical constantsusually associated with ITO, a half wave optical thickness of ITO(relative to 550 nm) when coated with, for example, chrome, will tend toproduce a reflection having a yellowish hue. Table 2a shows the sameeffect over a narrower range of ITO thicknesses and with a modifiedmetal stack. As the ITO is increased in thickness the reflectanceincreases providing a better intensity match. The a* value decreases andthe b* value increases. The net effect is that the color match will beimproved with the appropriate ITO thickness. Or if a color mismatch ischosen the color of the spectral filter material can be made to have alower b* value than the main reflective area.

TABLE 2 TCO plus Chrome Specular Included Trial a* b* C* A10Y  85CHR−6.801 2.486 7.241 44.829  80CHR −6.717 −0.829 6.768 44.375  75CHR−6.024 −4.031 7.248 43.759  70CHR −5.613 −5.426 7.807 42.917  65CHR−5.227 −6.639 8.45 42.64 100CHR −7.06 12.85 14.662 45.255

TABLE 2a Effect of ITO with modified metal stack Run # ITO Cr Ru Rh CrRu Rh CIE-D65 R a* b* 108 5 2.5 30 52.3 −2.5 −4.5 113 5 2.5 30 53.2 −3.1−3.0 118 5 2.5 30 54.0 −3.6 −1.3 123 5 2.5 30 54.5 −4.1 0.6 128 5 2.5 3054.9 −4.5 2.6 133 5 2.5 30 55.1 −4.7 4.7

Table 3 summarizes various color characteristics, namely, a*; b*; C* andY specular included (A10) for various indium-tin-oxide second surfaceconductive electrodes. The data contained in this table depicts theresulting values produced by varying the ITO thickness fromapproximately 65% to approximately 100% of a ½ wave thickness.

TABLE 3 TCO Specular Included Thickness Trial a* b* C* A10Y (Å)  65CLR−0.988 15.535 15.567 15.678 1095 100CLR 13.588 −17.765 22.366 8.967 1480 85CLR 8.376 2.896 8.863 11.352 1306  80CLR 4.481 11.34 12.193 12.8921253  75CLR 1.565 15.019 15.101 14.275 1194  70CLR −0.276 15.654 15.65615.259 1135

Materials used for transparent second surface conductive electrodes aretypically materials with an approximately 1.9 index of refraction, orgreater. It is known to minimize color impact of these conductiveelectrode materials by using half wave thickness multiples, using thethinnest layer possible for the application or by the use of one ofseveral “non-iridescent glass structures.” Non-iridescent structureswill typically use either a high and low index layer under the highindex conductive coating (see, for example, U.S. Pat. No. 4,377,613 andU.S. Pat. No. 4,419,386 by Roy Gordon), or an intermediate index layer(see U.S. Pat. No. 4,308,316 by Roy Gordon) or graded index layer (seeU.S. Pat. No. 4,440,822 by Roy Gordon) to minimize color impact. Theintensity of the ring with a color suppression layer is lower than thecenter of the part. The color suppression layer helps the color of thering but the ring would still be visible because of the intensitycontrast. The color suppressed ITO would therefore benefit from the useof a different sequence of metal layers on top of the ITO. Table 3ashows the color for a range of different metal options. The top chromelayer is optional, it does not contribute to the color or reflectancematch of the ring. The top chrome layer is added to minimize thetransmittance of the layer stack and to minimize the amount of UV lightthat would reach the seal, thus, extending the lifetime of the product.A chrome/rhodium/ruthenium stack is shown but it is understood thatother metals, alloys, high reflectors described elsewhere in thisdocument can be used.

The results of varying the thickness of the ITO with and without a colorsuppression layer are shown in Table 3a2. The colors shown in the tablerepresent the changes which occur with an ITO thickness between 100 and300 nm. Therefore, the use of a color suppression layer allows a broaderthickness range for the ITO layer without causing the strong colorvariations experienced without the color suppression layer.

TABLE 3a Effect of metal layers with color suppressed ITO - Reflectancein CIE-D65 Exam- Exam- Exam- Exam- Exam- Exam- ple 1 Example 2 ple 3Example 4 ple 5 Example 6 ple 7 Example 8 ple 9 Example 10 ple 11 Color80 80 80 80 80 80 80 80 80 80 80 Suppression Layer ITO ½ Wave 148.7148.7 148.7 148.7 148.7 148.7 148.7 148.7 148.7 148.7 148.7 Chrome Layer0 3 5 5 5 5 5 4 3 2 60 Rhodium 0 0 0 3 6 9 12 12 12 12 0 Ruthenium 30 3030 30 30 30 30 30 30 30 30 Chrome Layer 25 25 25 25 25 25 25 25 25 25 0Reflectance 48.8 49.2 49.3 51.1 52.2 52.9 53.2 54.3 55.5 56.8 45.7 Cap Ya* −2.2 −1.6 −1.4 −0.9 −0.5 −0.2 0.0 0.0 −0.1 −0.2 −1.8 b* 2.1 0.5 −0.3−0.3 −0.3 −0.2 −0.2 0.4 1.0 1.7 −3.3

TABLE 3a2 Effect of color suppressed ITO thickness on color - 200 nm ITO+/− 100 nm Case Case Case Case Case Case Stack 1 2 Case 3 4 5 6 7 Case 81.670 80 80 80 80 80 80 80 80 ITO 100 130 150 180 210 240 270 300 Chrome2 2 2 2 2 2 2 2 Rhodium 5 5 5 5 5 5 5 5 Ruthenium 30 30 30 30 30 30 3030 a* 1.15 0.54 −0.76 −1.5 0 0.54 −0.84 −1.1 b* 0.9 0.14 1.7 3.22 0.92−0.16 2.17 3.1 1.670 0 0 0 0 0 0 0 0 ITO 100 130 150 180 210 240 270 300Chrome 2 2 2 2 2 2 2 2 Rhodium 5 5 5 5 5 5 5 5 Ruthenium 30 30 30 30 3030 30 30 a* −1 −3.9 −3.4 5.5 8 −4 −10.1 −0.9 b* −5.4 3.19 9.9 3.8 −8.6−4.3 7.6 5.5

A partially transmissive layer such as thin chrome adjacent to the glassmay be used to provide adhesion benefits compared to metals that mightbe used for better reflectivity compared to chrome such as a platinumgroup metal (PGM) (i.e. iridium, osmium, palladium, platinum, rhodium,and ruthenium), Silver, Aluminum and various alloys of such metals witheach other, such as silver-gold, white gold, or other metals. When theseother metals or alloys are placed behind the partially transmissiveadhesion promoting layer, some of the improved reflectance of the secondmaterial will be realized. It may also be beneficial to overcoat thespectral filter material with a material that improves the durability ofthe spectral filter material whether it is in contact with a transparentconductor overcoat or if it is in direct contact with the electro-opticmedium. It should be understood that the reflector may be a dichroicstack. The spectral filter material may comprise a single material suchas chrome or may comprise a stack of materials such as: 1) chrome,rhodium, ITO; 2) moly; 3) chrome, rhodium, TCO; 4) chrome, platinumgroup metal, ITO; 5) ITO, silver, ITO; 6) ITO, silver alloy, ITO; 7)Z_(N)O, silver/silver alloy, Z_(N)O; 8) transparent conductor, metalreflector, transparent conductor; silicon, ITO 9) silicon, Z_(N)O, 10)chrome, ruthenium, ITO and 11) chrome/rhodium/ruthenium/ITO or othermetals, metal alloys or combinations described elsewhere in thisdocument can be used.

There may also be advantages to applying the transparent conductiveoxide(s) on the second surface of the mirror in more than one step. Forexample a Zinc oxide layer may be deposited initially to form a layer towhich silver or its alloys bond well. This is preferably chosen at athickness that produced a desirable color and reflectivity when combinedwith silver, silver alloy or other metals and their alloys. Then themetal layer(s) are applied around the perimeter of the part followed byadditional transparent conductive oxide(s) over at least theelectrochromic area. The additional applications of oxides improve theconductivity in the electrochromic area and may be chosen at athickness, which yields a desirable range of hue when going from brightstate to dark state, in the electrochromic area, but particularly in thefully darkened state. If the conductive oxide adjacent to theelectrochromic medium has sufficient conductivity, not all of the metaloxides in the stack would necessarily need to be conductive.

For example, using an optical model, opaque silver deposited over 100 nmof ITO, the color of a reflective ring would be about, using D65illuminant, 2 degree observer a*=−1, b*=−2 and Y value of 89. Forpurposes of this discussion, the silver is masked such that it is onlyapplied in a ring around the electrochromic area. The color of theelectrochromic area with only the 100 nm ITO on glass using a materialof index 1.43 as the electrochromic medium and no reflection from a3^(rd) or 4^(th) surface models as a*=−3, b*=8 with a Y value of 8. Tomake the electrochromic area less yellow and more conductive 40 nm ofITO coating may be added in the electrochromic area. This brings thecoating in the electrochromic area to about half wave optical thickness,which is approximately the second surface coating thickness that mostelectrochromic elements have. The model for the electrochromic area thenyields a color of a*=11, b*=−14, and Y value of 5. Either, or both, ofthese applications of transparent conductive oxides may be of anothermaterial such as aluminum doped zinc oxide. There might also beadditional layer(s) such as nickel chromium or nickel chromium suboxide,niobium or niobium suboxide, titanium or titanium suboxide, as well as,other means known in the art, that would protect or preserve a metallayer such as silver during subsequent steps of the coating and assemblyprocess such as thermal processing steps.

Note that by using such a stack, the reflective ring will more closelymatch the brightness of electrochromic areas in the undarkened statethat are more highly reflective such as devices that have 3^(rd) surfacecoatings incorporating silver or silver alloys.

In particular, Aluminum in direct contact with the electro-optic mediumtends to degrade upon being subjected to multiple coloring/clearingcycles. An overcoat of chrome has been demonstrated to improve thatdurability. When an ITO overcoat is used, a material such as silicon mayimprove the strength of the bond between the ITO and the substancescloser to the glass. Other materials, such as a platinum group metal(PGM) (i.e. iridium, osmium, palladium, platinum, rhodium, andruthenium), may be overcoated to improve adhesion reflection conductionelectrode stability, any one thereof, subcombiniations thereof orcombinations thereof, characteristics.

As revealed in the above figures and tables, the thickness of ITO may bechosen to produce a desired reflection color. If the ITO coating isabout 25% thinner, that is about 120 Ang. Instead of 140 Ang. then amore bluish hue results (i.e. lower b*). This, however, will also resultin decreased conductivity of the ITO coating. The reflectivity of thecoating will also be slightly, to somewhat, higher than for coatings ofthe traditional half wave optical thickness where the reference is to aminimum reflectivity near 550 nm.

The compromise between optimal color and sheet resistance of the ITO maybe mitigated by the use of partial deletion of the ITO layer. Forinstance, the ITO may be applied to any thickness needed to giveadequate color in the center of the viewing area and the required sheetresistance. Then the ring portion of the ITO coating may be ion etchedor removed in any other viable method so that the final thickness of theITO in the ring is at a point where we have the desired aesthetics. Theetching or removal process for the ITO may be conducted in the sameprocess as the deposition of the subsequent metal layers or it may bedone in a separate step.

It is known in the art that a chrome layer may be applied beneath theITO layer to provide a marginal match between the viewing area and thering. The degree of match between the ring in this case and the viewingarea is a function of the reflectance in the viewing area and propertiesof the chrome. What has not been taught in the art is how the propertiesof the chrome layer affect the match of the ring to the viewing area.For instance, in some cases, the reflectance of the viewing area may bespecified by law to be greater than 55%. The reflectance of the chromering is a function of the thickness of the chrome and, more importantly,the refractive index of the chrome. For a given refractive indexdispersion formula the reflectance can be dropped from its maximum valueby reducing the thickness of the chrome layer. This can have adetrimental effect because the transmittance of the chrome layer willincrease thus allowing more UV light to penetrate to the EC unit seal.The UV light can damage the seal leading to a shorter lifetime of theproduct.

The reflectance of the ring may be enhanced by tuning the opticalproperties of the chrome layer. Table 3b shows the dependence of thereflectance of chrome under ITO on the optical properties of the chromelayer. Two sets of optical constants were obtained from the openliterature and were mixed in different proportions to assess the effectof the optical constants on the reflectivity. The optical constants varywith wavelength and the values in Table 3b are values at 550 nm forreference. The thickness of the chrome layer is 80 nm and the ITO is148.7 nm. In at least one embodiment, the glass thickness is 1.2 mm andthe reflectance quoted is for viewing through the glass to the coatingstack.

The reflectance, in this example, varies from a low of 48.6 to a high of54.2%. This clearly demonstrates that some chrome layers may notnecessarily attain the reflectance needed for a match to the reflectancein the viewing when relatively high reflectance is present in theviewing area. In addition, there is a finite maximum reflectanceattainable by a single layer of chrome under the ITO. The preferredchrome layers are defined by the refractive indices of the chrome layer.

TABLE 3b Performance of the chrome layer under ITO versus chrome forvarious chrome optical constants Chrome 80 80 80 80 80 (nm) Layer Chromen 3.456 3.366 3.279 3.196 3.116 @550 nm Chrome k 3.981 4.089 4.199 4.3104.423 @550 nm ITO-B18 148.7 148.7 148.7 148.7 148.7 (nm) Reflectance48.6 49.9 51.3 52.8 54.2 (%)

In order to define the appropriate optical constants for the chromelayer a series of calculations were performed. A simplified analysis wasconducted where the refractive index of the chrome is held constant overthe visible region. The analysis shows the relationship between the realand imaginary refractive indices of the chrome and the resultantreflectance. In actual practice this may varied from theoreticalanalysis by up to +/−20% to account for the effects of the dispersion inthe Chrome optical constants. Table 3c shows the reflectance for variouscombinations of n and k and the ratio of n/k.

TABLE 3c Reflectance for chrome under ITO as a function of the opticalconstants of the chrome @550 nm Example n k ratio Reflectance 1 3.003.90 0.77 49.8 2 3.00 4.10 0.73 51.7 3 3.00 4.20 0.72 52.7 4 3.00 4.200.71 52.7 5 3.00 4.30 0.70 53.7 6 3.00 4.50 0.67 55.5 7 2.70 4.20 0.6454.2 8 2.90 4.20 0.69 53.1 9 3.00 4.20 0.71 52.7 10 3.00 4.20 0.72 52.711 3.10 4.20 0.74 52.2 12 3.50 4.20 0.83 50.9 13 3.70 4.20 0.88 50.4 143.90 4.20 0.93 50.1 15 4.10 4.20 0.98 49.8 16 3.30 4.20 0.79 51.5 173.30 3.90 0.85 48.7 18 2.70 3.50 0.77 46.8 19 2.70 3.70 0.73 49.0 202.70 3.90 0.69 51.2 21 2.70 4.10 0.66 53.2 22 2.70 4.30 0.63 55.2 232.70 4.50 0.60 57.2 24 3.30 4.04 0.82 50.0

An analysis of this data set was conducted to determine an equationrelating n and k to reflectance. Again the reflectance is calculatedwhen viewed through the glass.Reflectance=9.21972−8.39545*n+20.3495*k+1.76122*n^2−0.711437*k^2−1.59563*n*k

The results can also be shown graphically. Using the equation and/orgraph we can determine the needed n and k values necessary to attain adesired degree of reflectivity for a chrome layer.

Aesthetically, it is desirable for the ring to match the viewing area asclosely as possible. The eye is then not drawn to the ring and canbetter focus on the object in the viewing area. It is somewhatsubjective what difference in appearance between the ring and viewingarea is objectionable. The intensity between the ring and viewing areais preferably within 10%, more preferably within 6% and most preferablywithin 3%. Similarly, the color of the ring may be objectionable. Thecolor difference between the ring and viewing area should be less than30, preferably less than 15 and most preferably less than 10 C* units.

There may be situations where, due to processing limitation orrestrictions, it is not possible to attain the desired chrome opticalconstants but a match is still desired between the ring and the viewingarea. In other situations it may be desirable to attain a reflectancefor the ring which is higher than what is possible with chrome alone. Inthese circumstances an approach similar to what was discussed above forthe case of the metals on top of the chrome may be applied. To attainhigher reflectance a relatively thin layer of chrome is applied to theglass followed by a higher reflecting metal layer such as rhodium,ruthenium, iridium, cadmium, palladium, platinum or other appropriatemetal or alloy which has an inherent higher reflectance than chrome.

Table 3d shows the effect of chrome thickness on the reflectance for afixed n and k value for the chrome layer. The optical constants for thechrome were selected to produce a reflectance less than 50% with thegoal to match a viewing area reflectance of 56%. The reflectance varieswith the thickness of the first chrome layer with, essentially, aperfect match when the chrome layer thickness is reduced to 2.5 nm.

TABLE 3d Chrome thickness effect on reflectance Modified stack tocompensate for change in chrome properties Chrome optical constants n3.456 k 3.981 Chrome Layer 40 30 20 10 5 2.5 (nm) Ruthenium 35 35 35 3535 35 (nm) Chrome Layer 0 10 20 30 35 37.5 (nm) ITO-B18 148.7 148.7148.7 148.7 148.7 148.7 (nm) Reflectance 48.4 48.5 49.7 52.8 54.9 55.8(%)

The optical constants of the chrome layer also have an effect on thereflectance of this stack. The reflectance may be attenuatedsignificantly with the optical constants of the chrome but with the useof a thin chrome layer backed by a higher reflectance metal layer,ruthenium in this case, the reflectance may be significantly increasedcompared to the case where the high reflectance metal is not present.Table 3e shows the effect of optical constants of the chrome on thereflectance.

TABLE 3e Effect of Chrome optical constants on reflectance Effect ofChrome base layer optical constants on reflectance Chrome Layer 10 10 1010 Ruthenium 35 35 35 35 Chrome Layer 30 30 30 30 ITO-B18 148.7 148.7148.7 148.7 Reflectance 53.5 54.9 55.9 56.9 Chrome n 3.366 3.279 3.1963.116 Chrome k 4.089 4.199 4.310 4.423

Another option for enhancing the reflectance of the ring and improvingthe aesthetic match to the viewing area consists of putting a low indexmaterial between the ITO and the metal layers. The low index layer maybe silica, alumina, MgO, polymer or other suitable low index material.At least options for the low index material exist. A first is to controlthe thickness of the silica layer to provide an interferential increasein reflectance. Table 3f compares the color of the ring with and withoutthe addition of the low index layer. In this case, the low index layeris silica but as mentioned above any appropriate low index material issuitable for this application. The thickness of the ITO and low indexlayers may be adjusted to alter the color while simultaneouslyincreasing the reflectance. The reflectance may be further increased bycombining this technique with the different metal stacks describedelsewhere in this document.

TABLE 3f Effect of addition of low index layer between the ITO and metallayers Case 1 Case 2 ITO 125 125 SIO2 0 55 Chrome 60 60 R 46.6 54.2 a*−6.6 −0.5 b* 0.9 3.0

Another option is to insert a relatively thick low index materialbetween the ITO and the metal reflectors of the ring. In this case it isdesirable that the low index layer to be thick enough to act as a bulklayer. The necessary thickness is dependent, at least in part, on thematerial properties of the bulk layer, particularly if thein-homogeneities help to eliminate the phase information of the light.The thickness of the layer may be as thin as ¼ micron or thicker to getthe desired effect.

Other options to provide a match between the ring and the viewing areainclude the use of a High/Low/High dielectric stack. A series ofdielectric layers with alternating refractive indices may be used toprovide a high reflectance coating. For example, TiO2/SiO2/TiO2alternating layers may be used. Table 3g shows a stack consisting ofTiO2, SiO2 and ITO (thicknesses in nm) which provides a reflectance ofthe ring of 60.5% with a neutral color. The color and reflectance may bemodified by adjusting the thickness of the layers. A second option, withITO as the base layer, is also shown in Table 3g. The stack may beadjusted with both configurations to give both the desired color andreflectance values. The thickness of the ITO may be adjusted to providefor a more conductive layer. The thickness and indices of the otherlayers may be adjusted to compensate for the changes in the ITOthickness. This increases the utility of this design option.

TABLE 3g High/Low/High stack for ring match Glass 1.6 mm Glass 1.6 mmTIO2 55.3 ITO 148.7 SIO2 94.5 SIO2 90 TIO2 55.3 TIO2 50 SIO2 94.5 SIO290 ITO 148.7 TIO2 55 Reflectance 60.5 Reflectance 60.7 a* −5.3 a* −4.9b* 5.64 b* −1.9

Another option for the ring is the use of an IMI, orinsulator/metal/insulator, stack for the electrode. Some particular IMIstacks and ring materials are noted below but other versions are alsoviable. In the context of this invention, it may be assumed that an IMIstack may be substituted for ITO or another TCO. A metal or dielectricstack is then put between the IMI stack and the substrate or the sealmaterial. Both scenarios will work well. When the reflecting stack isput between the IMI and the glass, a more flexible situation for the IMIstack is achieved, particularly, if the metal reflectors are essentiallyopaque. The IMI is shielded by the metal reflectors and may be adjustedas needed for the center viewing area. When the IMI is in between theglass and the reflecting stack, it is desirable to ensure that therequirements in the viewing area and ring are compatible. This may beaccomplished but it does impose limitations on the IMI stack which arenot present when the reflectors are between the IMI and the glass.

In the IMI stack the insulator may be a dielectric layer such as TiO2,SiO2, ZnO, SnO2, Niobium oxide, silicon metal, ZrOx, SiN or othersuitable material. Mixed oxides, oxynitrides or other composites may beused. The metal is preferably Ag or an alloy of Ag. The Ag may bealloyed or doped with Au, Pd, Pt, Si, Ti, Cu or other materials selectedto provide the proper electrochemical, chemical or physical properties.Protective layers may be placed between the metal layer and thedielectrics to improve adhesion, chemical stability of the metal orthermal stability of the IMI coating during heat treatment. Multipledifferent dielectrics may be used to attenuate color and reflectance inthe viewing area and in the ring.

TABLE 3h IMI stacks and ring reflectance. Thicknesses are in nm unlessnoted Glass 1.6 mm Glass 1.6 mm Glass 1.6 mm Glass 1.6 mm Glass 1.6 mmGlass 1.6 mm Cr 45.0 Cr 30.0 Cr 20.0 Cr 0.0 Cr 0.0 Cr 40.0 ZnO 39.8 ZnO39.8 Ru 15.0 Ru 0.0 Ru 0.0 Ru 0.0 Ag 9.0 Ag 9.0 ZnO 39.8 ZnO 39.8 TiO223.5 TiO2 23.5 ITO 52.8 ITO 52.8 Ag 9.0 Ag 9.0 ZnO 10.5 ZnO 10.5 Cr 0.0Cr 0.0 ITO 52.8 ITO 52.8 Ag 9.0 Ag 9.0 R 54.2 R 53.2 Cr 0.0 Cr 10.0 ITO35.7 ITO 35.7 a* −4.9 a* −5.6 R 55.9 AL 40.0 Ru 0.0 Ru 0.0 b* 0.5 b* 1.3a* −4.3 R 57.5 Cr 25.0 Cr 0.0 b* 0.9 a* −1.5 R 54.3 R 55.1 b* 8.4 a*−3.4 a* −5.0 b* −0.2 b* 0.8

When the ITO thickness is increased from a ½ wave to the point where abluish color is achieved for the ITO plus chrome stack, the color ismuch more susceptible to shifts due to thickness variations duringdeposition and, or, due to viewing angle differences in actual use. ITOcoatings deposited intentionally thinner than ½ wave optical thickness,per the discussion above also exhibited relatively low levels of hazewhen overcoated with chrome as depicted in Table 2.

The difference between coatings may be measured by using the specularexcluded option available on some reflectance spectrophotometers. It isimportant to check that such measurements are actually measuringscattered light and not primarily small amounts of the specularcomponent. In general, shorter wavelengths of light scatter morereadily. That fact is a good indicator when used to determine whether agiven reading is actually the expected scattered light intensity beingmeasured. A MacBeth Color Eye 7000 is one spectrophotometer that givesgood haze measurement results in this regard.

As used herein, the terms “haziness” and “haze” should be understood torefer to the property of scattering, or non-specular reflection, in thinfilms. Haziness may be caused by a number of factors, including, lessthan fully oxidized layers, crystal sizes within a layer, surfaceroughness, layer interface properties, quality of cleaning of thesubstrate, subcombinations thereof and combinations thereof.

These properties may vary due to processing conditions and/or thematerials. This is especially true with processing conditions, in thatthe level of haze may vary substantially even within a single process“batch” or “load” of coatings. Nonetheless, for an ITO layer overcoatedwith chrome and viewed through the glass, whether with or without colorsuppression or anti-iridescent underlayers, it has been shown to bepossible to produce coatings much less hazy than those similarlyobtained with Tec 15 glass from Libbey Owens Ford.

Aluminum oxide may be used as an underlayer to assist in controlling thehue of the spectral filter material stack, as well as, mixtures ofoxides yielding an appropriate refractive index. It may be particularlyadvantageous to use a mixture of ITO and SiO₂ and, or, SiO as anunderlayer for ITO to control the resulting hue of the spectral filtermaterial stack. The use of ceramic targets for ITO is often consideredcapable of tighter process control for properties such as filmthickness. A sputter target comprising ITO and Si and, or, Si in amixture of oxidation states may be employed. Such an underlayerpotentially enables one to use an in line coating system that does nothave substantial gas flow isolation from either pumping or interveningdoors, between the cathodes used for depositing the underlayer and theITO layer. A mixture of ITO and SiO₂ to at least some percentage of SiO₂will retain sufficient conductivity such that RF sputtering is notnecessary. Radio Frequency (RF) sputtering compared to Medium Frequency(MF) sputtering, direct current (DC) sputtering, often requireselectrical isolation and impedance matching that is not trivial toinclude in a thin film coating system.

Since there are regulatory requirements for 35% (40% in many EuropeanCountries) reflectivity for vehicular rearview mirrors, (clear state forelectro-optic mirror elements), in order for the perimeter area to beincluded in the field of view calculations it needs to have such a levelof reflectance. In the data provided herein with respect to chrome overTec 15 glass, this minimum is not met.

Use of a measurably hazy CVD deposited flourine doped tin oxide that ispart of an anti iridescent structure for use in electro-optic devices isknown. Various thicknesses of ITO are known for providing a conductiveelectrode. It has not previously been known that the b* of anindium-tin-oxide conductive electrode and chrome spectral filtermaterial stack may be predictably controlled by varying the thickness ofthe ITO. Pyrolitically deposited Fluorine doped tin oxide with an antiiridescent structure (Tec 15 from L.O.F) is substantially more hazy whenovercoated with chrome compared with ITO deposited over a layer ofaluminum oxide as shown in Table 1.

In embodiments where the spectral filter material is located proximatethe first surface it can be advantageous to minimize the distancebetween the first surface and the third or fourth surface reflector. Thegreater the distance between the reflector and the first surface, thegreater the discontinuity will be in the image reflected by the elementwhen transitioning from the main reflector to the spectral filtermaterial. This will be accentuated as the viewing angle increases.

In embodiments where a spectral filter material is located proximate thesecond surface of the element and an additional coating, such as ahydrophilic coating, is on the first surface, the optical properties ofboth coatings will affect the appearance of the perimeter of the deviceand may require adjustments to the layers for optimal appearance of theperimeter. In the case of an electro-optic element with a hydrophiliccoating as described in commonly assigned U.S. Pat. Nos. 6,447,123,6,193,378 and application Ser. No. 09/602,919 hereby incorporated intheir entireties by reference, the first surface coating will have areflectance substantially lower than the reflectance of the preferredembodiments of a second surface spectral filter material as describedherein. This will result in the hue and, or, chroma of the color of theperimeter of the device being more dependent on the second surfacecoatings than those on the first surface. Nonetheless, especially whencolor is chosen near a point of transition from perceived yellowish tobluish, +b* to −b*, respectively, or reddish to greenish, +a* to −a*,respectively, these differences tend to become more perceivable. Whenattempting to match the hue of the spectral filter material to that ofthe overall field of view of the reflector, small differences in thematerials that result in transitions from more yellow to less yellow, orless blue to more blue, when compared to the overall field of view ofthe element may be avoided by practicing the teachings herein. A similarcontrast in reddish or greenish hue may be managed.

For example, the color and reflectance of the ring and viewing area withand without a hydrophilic surface coating were modeled with a thin filmprogram. The spectral filter ring consists of 126 nm of ITO, 3 nm of Cr,5 nm of Rh, 30 nm of Ru and 40 nm of Cr. The exit medium or materialnext to the metals and dielectric layers is an electrochromic fluid withan index of approximately 1.365. The hydrophilic layer consists of a 65nm color suppression layer next to the glass, a 234 nm TiO2 layer with asurface morphology and 10 nm of SiO2.

Table 4a shows the reflectance and color of various portions of themirror. The first two rows show the effect of the presence or absence ofthe hydrophilic layer on the appearance of the ring. The color andreflectance are essentially unchanged with the application of thehydrophilic layer on the first surface of the mirror. In rows 3 and 4 wesee the change of color in the viewing area when the mirror is in thedarkened state. In the undarkened state the higher reflectance of theback reflector dominates the appearance. The reflectance increases withthe hydrophilic layer which may have advantages in certain markets. Thecolor of the viewing area without the hydrophilic layer in this case issomewhat objectionable because of the thickness of the ITO is selectedto optimize the color of the ring. This results in a somewhatcompromised color in the viewing area. By adding the hydrophilic coatingon surface one the color becomes more neutral, a positive benefit to thecombination. The fifth row shows the color of the hydrophilic layerwithout any other coatings on surface two of the glass and with anelectrochromic fluid as the exit medium for reference.

TABLE 4a Color and reflectance of different mirror components StructureR a* b* Hydro/Glass/ITO/Cr/Rh/Ru/Cr 58.46 −4.20 3.23Glass/ITO/Cr/Rh/Ru/Cr 58.23 −4.20 1.96 Hydro/Glass/ITO 13.50 0.69 −3.10Glass/ITO 5.65 4.69 1.92 Hydro/Glass 12.47 −1.70 −4.60Example Mirror Element Description

A particularly advantageous element configuration in conformance withFIGS. 4 a-4 c and 5 comprises a first substrate of glass approximately1.6 mm thick having a conductive electrode approximately 0.4 wavelengths(approximately 80% of ½ wave) thick of indium-tin-oxide applied oversubstantially the entire second surface by sputtering. At least aportion of the first corner, the edge and the second corner are treatedsuch that approximately 0.25 mm of material is removed from the secondsurface and approximately 0.5 mm of material is removed from the firstsurface. It should be apparent that a portion of conductive electrode isremoved during treatment. A spectral filter material approximately 400 Åthick of chrome is applied approximately 4.5 mm wide near the perimeterof the first substrate proximate the conductive electrode. An electricalconduction stabilizing material approximately 100 Å thick of a platinumgroup metal (PGM) (i.e. iridium, osmium, palladium, platinum, rhodium,and ruthenium) is applied approximately 2.0 cm wide near the perimeterof the first substrate proximate the spectral filter material. A firstseparation area is laser etched approximately 0.025 mm wide with aportion thereof extending parallel to, and within the width of, aportion of a primary seal material area to substantially electricallyinsulate the first and second conductive electrode portions, spectralfilter material portions and adhesion promotion material portions. Asecond substrate of glass approximately 1.6 mm thick having a conductiveelectrode approximately 0.5 wavelengths thick over substantially all ofthe third surface is provided. A second separation area is laser etchedapproximately 0.025 mm wide with a portion thereof extending parallelto, and within the width of, a portion of a primary seal material tosubstantially electrically insulate the third and fourth conductiveelectrode portions. A reflective material approximately 400 Å thick ofchrome is applied proximate the third conductive electrode portionsubstantially defined by the inboard edge of the primary seal. Anoptional overcoat approximately 120 Å thick of ruthenium is appliedproximate the reflective material substantially defined by the inboardedge of the primary seal. A primary seal material, comprising an epoxyhaving a cycloaliphatic amine curing agent and approximately 155 μmsubstantially spherical glass balls, is provided to secure the first andsecond substrates together in a spaced apart relation to define achamber. A substantially rigid polymer matrix electro-optic medium, astaught in many commonly assigned U.S. patents and patent applications,the disclosures of which are incorporated in their entireties herein byreference, is provided between the first conductive electrode portionand the optional overcoat material within the chamber through a plugopening in the primary seal material. The plug opening is sealinglyclosed using ultra-violet light curable material with UV lightirradiating the plug bottom thru the third and fourth surface. The curedprimary seal material and the plug material are inspected by viewing theelement looking toward the fourth surface. An electrically conductivematerial comprising a bisphenol F epoxy functional resin, viscosity ofapproximately 4000 cP, having a cycloaliphatic amine curing agent,viscosity of approximately 60 cP, and a silver flake, tap densityapproximately 3 g/cc and average particle size of approximately 9 μm, isapplied proximate the outboard edge of the primary seal material betweenthe second adhesion promotion material portion, the third conductiveelectrode portion and the first electrical clip. This same electricallyconductive material is applied proximate the outboard edge of theprimary seal material between the first adhesion promotion materialportion, the fourth conductive electrode portion and the secondelectrical clip. A double sided, pressure sensitive, adhesive materialis provided between the electrical clip and the fourth surface of thesecond substrate. The electrically conductive material is cured afterplacement of the first and second electrical clips. The primary sealmaterial is partially cured prior to application of the electricallyconductive material; additional primary seal material curing coincideswith curing the electrically conductive material. This curing process isbeneficial to prevent warping of the element and improves overallrelated adhesion, sealing and conductivity characteristics.

This example mirror element description is provided for illustrativepurposes and in no way should be construed to limit the scope of thepresent invention. As described throughout this disclosure, there aremany variants for the individual components of a given element andassociated rearview mirror assembly.

In embodiments of the present invention having a highly reflectivespectral filter material applied between the second surface of the firstsubstrate and the primary seal, it has proven advantageous to usespecifically selected spacer material to eliminate bead distortion.Glass beads are typically added to the primary seal material to controlthe spacing between the substrates that form the chamber containing theelectro-optic medium. The diameter of, preferably substantiallyspherically shaped, glass beads is a function of the desired “cell”spacing.

These glass beads function well as spacers in electro-optic devices thathave two transparent substrates, a transparent front substrate and areflector positioned on surface three or four. These spacers alsofunction well in devices with a spectral filter material on the firstsurface or within the first substrate. However, when the spectral filtermaterial is applied proximate the primary seal material and the secondsurface, “dimples” or small distortions in the chrome spectral filtermaterial are created by typical glass spacer beads and are visible inthe seal area of a resulting mirror element. These dimples are alsovisible in mirror elements having a third surface reflector, however,they can only be seen if the mirror element is viewed looking at thefourth surface. These third surface dimples in a reflector are notvisible in a resulting mirror element when viewed once installed in avehicle.

In contrast, these dimples are readily visible in a resulting mirrorelement when the spectral filter material is proximate the secondsurface and covers the primary seal material area. These dimples arecreated, at least in part, by high stress areas proximate the glassspacer beads. Typically, the primary seal material comprises asubstantially rigid thermal curing epoxy; preferably comprising acycloaliphatic amine curing agent. The curing temperature of the epoxymaterial is often greater than 150 degrees Centigrade. There is often asignificant difference in thermal expansion between the customarily usedceramic glass bead (low coefficient of thermal expansion) and the epoxymaterial (high coefficient of thermal expansion). At least a portion ofthe glass spacer beads are in contact with the top material of arespective stack of materials proximate the second and third surfaces ofthe substrates when the seal solidifies and cures at high temperatures.As the mirror element cools in the post primary seal material curecycle, the seal material shrinks much more than the spacer beads andstress develops around the bead creating a distorted area, or dimple, inthe substrate stack. When the substrate comprises a reflector on asurface that is in contact with the primary seal material, thesedistorted areas, or dimples are visually perceptible.

These distorted areas can be eliminated in a number of ways. A moreelastomeric or flexible primary seal material may be used thatinherently does not build areas of high stress. A spacer that is morecompressible may be used such that the spacer flexes as stress develops.A breakable spacer may also be used such that the spacer breaks torelieve the localized stress during primary seal material curing. A roomor low temperature curing seal material with low cure shrinkage may beused that will eliminate or minimize the thermal expansion relatedstress. A seal material and spacers that are a closer match in thermalexpansion may be used to eliminate or minimize the thermal expansionrelated stress plastic spacer beads and plastic seal material, ceramicspacer beads and ceramic seal material or seal material and/or spacerbeads containing a thermal expansion modifying filler. The spacer beadsin the seal material may be eliminated all together if proper methods ofelement manufacturing are used to control the element gap (“cell”spacing). For example, a spacing media such as a PMMA bead or fiber thatdissolves in the electro-optic media could be applied to the areainternal the primary seal to control the element gap during primary sealmaterial curing. The element substrates may also be held apartmechanically until the seal solidifies.

Example 1 Primary Seal with Spacers

A master batch of thermal cure epoxy was made using 96 parts by weightDow 431 epoxy novolac resin, 4 parts fumed silica and 4 parts 2 ethyl 4methyl imidazole. To small portions of the above master batch 2 parts byweight of the following spacer materials were added. A dab of theepoxy/spacer mixture was then put on a 1″×2″×0.085″ thick piece ofchrome coated glass such that the epoxy mixture was in contact with thechrome reflector. A 1″×1″×0.85″ piece of ITO coated glass was placed ontop and the glass sandwich was clamped such that the glass piecesbottomed out to the spacer material. The element was then cured at about180 degrees Centigrade for about 15 minutes. Subsequently, once theelement returned to room temperature, it was visually inspected fordimples looking at the chrome as if it were on surface two.

Example 2 Primary Seal Material

Using the thermal Cure Epoxy of Example 1 plus 140 um Glass Beads causeda very heavy dimple pattern to be visible

Example 3 Primary Seal Material

Using the thermal Cure Epoxy of Example 1 plus Plastic Beads(Techpolymer, Grade XX-264-Z, 180 um mean particle size, SekisuiPlastics Co. Ltd., Tokyo, Japan) caused no dimple pattern to be visible.

Example 4 Primary Seal Material

Using the thermal Cure Epoxy of Example 1 plus Plastic Fibers (Trilene,140 um diameter monofilament line cut to 450 um lengths, Berkley, SpringLake, Iowa) caused no dimple pattern to be visible.

Example 5 Primary Seal Material

Using the thermal Cure Epoxy of Example 1 plus Hollow Ceramic Beads(Envirospheres, 165 um mean particle size, Envirospheres PTY Ltd.,Lindfield, Australia) caused very slight but acceptable dimple patternto be visible.

Example 6 Primary Seal Material

Using an epoxy cured at room temperature caused no dimple pattern to bevisible after 1 week at room temperature.

Example 7 Primary Seal Material

Using two parts by weight glass beads (140 um) added to a UV curableadhesive, Dymax 628 from Dymax Corporation, Torrington Conn., and theadhesive was compressed between two glass substrates as described abovecaused a very slight but acceptable dimple pattern to be visible. Theadhesive was UV cured at room temperature.

Turning to FIGS. 7 a-n there are shown various options for selectivelycontacting a particular portion of the second and third surfaceconductive electrode portions 705, 710. As can be appreciated, theconfiguration of FIG. 5 results in the electrically conductive materialcontacting at least a portion of each the second and third surfaceconductive electrode portions.

The element construction depicted in FIG. 7 a comprises a firstsubstrate 702 a having a second surface stack of materials 708 a and asecond substrate 712 a having a third surface stack of materials 722 a.The third surface stack of materials is shown to have an isolation area783 a such that a portion of the third surface stack of materials thatis in contact with a conductive epoxy 748 a is isolated from theremainder of the third surface stack of materials. The first and secondsubstrates are held in spaced apart relationship to one another via aprimary seal material 778 a. It should be understood that another sideof the element may have a similar isolation area associated with thesecond surface stack of materials for providing contact to the thirdsurface stack of materials within the viewing area. It should beunderstood that either the second or third surface stack of materialsmay be a single layer of on materials as described elsewhere herein andwithin references incorporated herein by reference.

The element construction depicted in FIG. 7 b comprises a firstsubstrate 702 b having a second surface stack of materials 708 b and asecond substrate 712 b having a third surface stack of materials 722 b.The first and second substrates are held in a spaced apart relationshipwith respect to one another via a primary seal material 778 b. Anelectrically conductive epoxy 748 b is in contact with the third surfacestack of materials and electrically insulated from the second surfacestack of materials via the insulating material 783 b. It should beunderstood that another side of the element may have a similar isolationarea associated with the second surface stack of materials for providingcontact to the third surface stack of materials within the viewing area.It should be understood that either the second or third surface stack ofmaterials may be a single layer of on materials as described elsewhereherein and within references incorporated herein by reference.

The element of FIG. 7 c comprises a first substrate 702 c having asecond surface stack of materials 708 c and a second substrate 712 chaving a third surface stack of materials 722 c. The first and secondsubstrates are held in spaced apart relationship with respect to oneanother via a primary seal material 778 c. The second surface stack ofmaterials extends toward the edge of the first substrate beyond theprimary seal material such that it is in electrical contact with a firstelectrically conductive epoxy, or first solder, 748 c 1. The thirdsurface stack of materials extends toward the edge of the secondsubstrate beyond the primary seal material such that it is in electricalcontact with a second electrically conductive epoxy, or second solder,748 c 2. It should be understood that another side of the element mayhave a similar isolation area associated with the second surface stackof materials for providing contact to the third surface stack ofmaterials within the viewing area. It should be understood that eitherthe second or third surface stack of materials may be a single layer ofon materials as described elsewhere herein and within referencesincorporated herein by reference.

FIG. 7 d depicts the second surface electrical contact 748 d 1 beingmade on an opposite side of the element from a third surface electricalcontact 748 d 2. FIG. 7 e depicts the second surface electrical contact748 e 1 being made on a side of the element and the third surfaceelectrical contact being made on an end of the element. FIG. 7 f depictsthe second surface electrical contact 748 f 1 being made on one side andcontinuously with one end of the element and the third surfaceelectrical contact 748 f 2 being made on an opposite side andcontinuously with an opposite end of the element. Fig. g depicts thesecond surface electrical contact 748 g 1 being made on opposite sidesof the element and the third surface electrical contact 748 g 2 beingmade on an end of the element. FIG. 7 h depicts the second surfaceelectrical contact 748 h 1 being made on opposite sides of the elementand the third surface electrical contact 748 h 2 being made on oppositeends of the element. FIG. 7 i depicts the second surface electricalcontact 748 i 1 being made continuously on opposite ends and one side ofthe element and the third surface electrical contact 748 i 2 being madeon one side of the element. It should be understood that, in at leastone embodiment, the longer electrical contact will correspond to thesurface having the highest sheet resistance stack of materials. Itshould be understood that the electrical contact may be via electricalconductive epoxy, solder or an electrically conductive adhesive.

FIG. 7 j depicts an element comprising a first substrate 702 j having asecond surface stack of materials 708 j and a second substrate 712 jhaving a third surface stack of materials 722 j. The first and secondsubstrates are held in spaced apart relationship with respect to oneanother via perimeter first and second primary seals 748 j 1, 748 j 2.The first primary seal functions to make electrical contact with thesecond surface stack of materials and the second primary seal functionsto make electrical contact with the third surface stack of materials.The first and second primary seals hold the first and second substratesin a spaced apart relationship with respect to one another andpreferably both primary seals are substantially outside the edge of eachsubstrate.

With reference to FIG. 7 k, a profile view of a portion of a rearviewmirror element is depicted comprising a first substrate 702 k having atleast one layer 708 k of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 k having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 k to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 k is located within saidchamber. In at least one embodiment, the third surface stack ofmaterials comprises an underlayer 718 k, a conductive electrode layer720 k, a metallic layer 722 k and a conductive tab portion 782 k havingan overlap portion 783 k underneath the metallic layer and primary sealmaterial. It should be noted that the conductive tab portion 782 k couldalternatively be deposited over the metallic coating 722 k to create theoverlap portion. In at least one embodiment, the underlayer istitanium-dioxide. In at least one embodiment, the underlayer is notused. In at least one embodiment, the conductive electrode layer isindium-tin-oxide. In at least one embodiment, the conductive electrodelayer is omitted. In at least one embodiment, the conductive electrodelayer emitted and the underlayer is either a thicker layer oftitanium-dioxide or some other substantially transparent material havinga relatively high index of refraction (i.e. higher index of refractionthan ITO), such as, silicon carbide. In at least one embodiment, theconductive tab portion comprises chrome. It should be understood thatthe conductive tab portion may comprise any conductive material thatadheres well to glass and is resistant to corrosion under vehicularmirror testing conditions. As can be appreciated, when the third surfacestack of materials, or at least those layers within the stack that aresusceptible to corrosion, are kept within an area defined by an outeredge of the primary seal material, the element will be substantiallyimmune to problems associated with third surface corrosion. It should beunderstood that the layer, or layers, susceptible to corrosion mayextend beyond the primary seal material provided a protective overcoator sealant is incorporated, such as, conductive epoxy or an overcoatlayer. It should be understood that any of the first, second, third andfourth surface layers or stacks of materials may be as disclosed hereinor within the references incorporated elsewhere herein by reference. Itshould be understood that the conductive tab portion improvesconductivity over the conductive electrode; as long as a conductiveelectrode layer is provided with sufficient conductivity, the conductivetab portion is optional. In at least one embodiment, the conductiveelectrode layer imparts the desired color specific characteristics ofthe corresponding reflected light rays in addition to providing thedesired conductivity. Therefore, when the conductive electrode isomitted color characteristics are controlled via the underlayer materialspecifications.

Turning to FIG. 7 l, a profile view of a portion of a rearview mirrorelement is depicted comprising a first substrate 702 l having at leastone layer 708 l of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 l having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 l to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 l is located within saidchamber. In at least one embodiment, the third surface stack ofmaterials comprises an underlayer 718 l, a conductive electrode layer720 l, a metallic layer 722 l and a conductive tab portion underneaththe primary seal material. In at least one embodiment, a void area 783 lis defined between the metallic layer and the conductive tab portion,the conductive electrode provides electrical continuity there between.In at least one embodiment, the underlayer is titanium-dioxide. In atleast one embodiment, the underlayer is not used. In at least oneembodiment, the conductive electrode layer is indium-tin-oxide. In atleast one embodiment, the conductive tab portion comprises chrome. Itshould be understood that the conductive tab portion may comprise anyconductive material that adheres well to glass and is resistant tocorrosion under vehicular mirror testing conditions. As can beappreciated, when the third surface stack of materials, or at leastthose layers within the stack that are susceptible to corrosion, arekept within an area defined by an outer edge of the primary sealmaterial, the element will be substantially immune to problemsassociated with third surface corrosion. It should be understood thatany of the first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

With reference to FIG. 7 m, a profile view of a portion of a rearviewmirror element is depicted comprising a first substrate 702 m having atleast one layer 708 m of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 m having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 m to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 m is located within saidchamber. In at least one embodiment, a first metallic layer 718 m isdeposited over substantially the entire third surface. In at least oneembodiment, a second metallic layer 720 m is deposited over the firstmetallic layer such that an outer edge of the second metallic layer islocated within an area defined by an outer edge of a primary sealmaterial 778 m. In at least one embodiment, the first metallic layercomprises chrome. In at least one embodiment, the second metallic layercomprises silver or a silver alloy. It should be understood that any ofthe first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

Turning to FIG. 7 n, a second substrate 712 n is depicted comprising astack of materials having an eyehole 722 n 1 substantially in front of alight sensor or information display. In at least one embodiment, a firstmetallic layer 718 n is provided with a void area in the eyehole area.In at least one embodiment, a second metallic layer 720 n is providedwith a void area in the eyehole area. In at least one embodiment, athird metallic layer 722 n is provided. In at least one embodiment, onlythe third metallic layer is deposited in the eyehole area. In at leastone embodiment, the first metallic layer comprises chrome. In at leastone embodiment, the second metallic layer comprises silver or silveralloy. In at least one embodiment, the third metallic layer comprises athin silver, chrome or silver alloy. It should be understood that any ofthe first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

One way the spectral filter material 715, proximate a first surfaceconductive electrode, can be electrically insulated from otherconductive electrode portions is by overcoating at least portions of thespectral filter material with an organic or inorganic insulatingmaterial as depicted in FIG. 7 b.

When a spectral filter material, such as chrome metal, is applied on topof the transparent conductor of the second surface through a mask in acoating operation (such as by vacuum sputtering or evaporation etc.), anon-conductive coating may be applied through a mask in the same processto electrically isolate the second surface conductive electrode from thethird surface conductive electrode in the conductive seal area.

Example 1 Insulating Material

A spectral filter material comprising metal, metal alloy, layers ofmetals, layers of metal alloys or combinations there of, such as chrome,molybdenum, stainless steel, or aluminum, rhodium, platinum, palladium,silver/gold, white gold and ruthenium, often over an adhesion promotionmaterial such as chrome, is vacuum deposited through a mask over atransparent conductor (such as ITO) to cover the seal area. Aninsulating material such as silicon, silicon dioxide, chromium oxide,aluminum oxide, titanium oxide, tantalum oxide, zirconium oxide, oryttrium oxide can be applied with use of a mask over top the metal layerto electrically isolate the desired spectral filter material area fromother conductive portions. This electrical insulation material is notapplied to, or removed from, portions of the spectral filter material oradmission/conductivity promotion material where electrical conductivityis desired.

One method to reduce the size of, or to eliminate the need for, thebezel is to make an element with substantially no offset between theperipheral edges of the first and second substrates using anelectrically conductive material as a portion of the electrical bus. Inorder to use the preferred electrically conductive material, anisolation of a portion of the conductive materials on the second and,or, third surfaces needs to take place. The second and third surfaceswould be shorted together by the electrically conductive material if oneportion of each surface were not isolated in non-overlapping areas. Thethird surface may be electrically isolated on one side of the elementand the second surface would be electrically isolated on an opposite oradjacent side of the element. Preferably, a laser is employed to removeconductive material from the desired areas. The laser separation ispreferably located between the electrically conductive material and thevisibly active area of the element. More preferably the separation areais located such that an anode and cathode are not coexistent on the samesurface and in contact with the electro-optic medium. When an anode andcathode are located on the same surface with the addition of an anode ora cathode on the adjacent surface, a residual slow to erase color willbe present along the separation area. Additionally, with an anode on thesecond surface and the third surface between the seal and the separationarea, the color produced by the anode is visible between the primaryseal material, and the separation area. Likewise if a cathode is locatedon the third surface and the second surface between the primary sealmaterial and the separation area the color produced by the cathode isvisible from the front between the separation area and the primary sealmaterial.

In mirror elements having a spectral filter material between the viewerand the primary seal material a separation area may be incorporated.With the spectral filter material on the first surface the mirrorelement is made much the same as described with regards to elements thatdo not include a spectral filter material. The separation areas are notvisible when looking at the first surface. When the spectral filtermaterial is proximate the second surface the separation area is visiblewhen looking at the first surface.

A typical laser defined separation area is between 0.005-0.010 incheswide. By making the separation area 0.002-0.004 inches wide it is muchless noticeable. Even more preferable would be an isolation line of lessthan 0.002″ so as to be virtually unnoticeable from the driver'sperspective. Material can be removed to create an electrical isolationline using a variety of techniques including masking during coatingdeposition, media blasting, laser ablation, mechanical abrasion,chemical etching, or other methods known in the art. Photolithography incombination with chemical, reactive ion or other etching method couldproduce isolation lines below 1 um in width. It should also be notedthat shorter wavelength lasers can be focused to create a smaller spotsize. This provides for a more narrow and less visible electricalisolation line. As the isolation line becomes more narrow, it may becomeincreasingly difficult to achieve complete electrical isolation betweenthe first and second conductive portions. The resistance between the twoconductive portions can be easily measured using an ohmmeter. For atypical electro-optic mirror element it is preferred that thisresistance is greater than 30 ohms. It is more preferred that thisresistance is greater than 100 ohms. Complete electrical isolation ismost preferred. The separation area is preferably located within theprimary seal material area, and extending the length of the element toprovide a large electrical contact area. When the separation area islocated over the top of the primary seal material area, the color, ortransparency of the seal can be adjusted to help hide the separationarea. This separation area may be incorporated into artwork or text onthe mirror element. A separation area may be incorporated into adisclaimer on the mirror element, a manufacturers emblem, or othergraphic and, or, text. It should be understood that the laser line maybe positioned along the inner edge of the spectral filter material. Inthis configuration, the majority of the laser line is not visiblebecause the laser line coincides with the edge of the spectral filtermaterial. Some residual color is present after clearing theelectro-optic media on the same substrate, however, most of the coloredarea is hidden from view behind the spectral filter material. The onlylaser line portions that are visible are short line segments madethrough the spectral filter material near the edge in two places.

It is also generally desirable to position the electrode isolation line,such as a laser ablation line in an area of the mirror, outside of thespecified field of view of the mirror. There are legal guidelines in theUnited States, Europe and in other countries for the minimum area to theside and rear of a vehicle that must be visible in a mirror. This areacan be projected onto the surface of the mirror and objects that arewithin the boundaries of that projection must be visible to the driver.This projection generally takes the shape of a triangle and the size ofthe projection can be larger or smaller depending on whether the mirrorsurface in flat or bent. FIG. 2 a details the shape (identified withdashed line 211 a) of a typical specified minimum field of viewprojection for a left hand outside electrochromic mirror with a bezel.Since the bezel area is not reflective it cannot be included in thefield of view of the mirror. However, the bezel area can be covered witha spectrally reflective coating such as a metallic ring on surface two.As long as this reflective ring has a high enough reflectance to meetthe minimum reflectance standards for the particular country, this areacould be considered field of view. As described previously the mirrorcould then be made smaller by the bezel width while maintaining the samespecified field of view. Again, it would be preferable to locate anyvisible electrode isolation lines outside of the projection of thespecified field of view of the mirror.

Another way to isolate the electrically conductive material is to use anonconductive layer between the electrically conductive material and thesurface to be isolated, such as a vacuum deposited dielectric ink, or athinned layer of a nonconductive epoxy or other resin. It may bedesirable to employ a separation area proximate the third surfacebecause the separation area is not visible looking at the first surface.By using a nonconductive material on the second surface there is no needfor a first separation area. This is particularly desirable when thesecond surface has a spectral filter material. By thinning anonconductive epoxy a very thin layer can be obtained. This is importantbecause enough area needs to be provided to apply the electricallyconductive material. Preferably, the nonconductive epoxy is only flashcured. For example, place the material in an 85 c oven for approximatelytwo minutes. If the nonconductive epoxy is fully cured and is partiallycovering an area that is in contact with the primary associated spacerbeads undesirable, non-uniform, cell spacing may be created. By notcuring the nonconductive material completely the spacer beads will moreeasily penetrate the layer during the finale cure, and not affect thecell spacing.

An external electrical connection may be made to the third surface of anelectro-optic mirror element having a second surface spectral filtermaterial by extending at least a portion of the third surface conductiveelectrode under the primary seal material area and over the perimeteredge of the second substrate. When coating (such as by vacuumsputtering) over the edge of a piece of glass, the conductivity of thecoating tends to decrease over a sharp edge or rough surface, also thecoating process does not typically provide a durable coating on the sideor edge of the glass. To do this without losing conductivity, a goodseam or polish on the substrate corner and, or, edge is helpful toprovide a smooth transition from the third surface to the edge. A roughground surface without polishing has lower conductivity at a typicalthird surface coating thickness. The smoother the surface and transitionfrom the third surface to the edge, the better the conductivity. Asputter target mounted to coat the edge of the glass during the coatingprocess is also helpful to provide a more uniform and durable coating.

It is conceivable that the coating could be extended over the edge ofthe glass and onto the back of the glass such that the electricalconnection to the third surface could be made on that back of the mirrorelement. A reflective third surface is typically more conductive than asecond surface conductive electrode, therefore, an electricallyconductive material may not be needed. Therefore, the primary sealmaterial may be dispensed up to the edge of the substrate. Having thethird surface material extending onto the edge may only be on one side.The opposite substrate may comprise a separation area and electricallyconductive material to the third surface since it is not visible.

With the third surface material extended onto the edge of the substrate,an L clip in lieu of a J clip, can be used since there is no need tohave a clip portion inserted between the second and third surfaces. TheL clip only needs to be long enough to contact the conductive portion onthe edge. A conductive epoxy could be used to bond to the third surfacematerial on the edge to the L clip. A pressure sensitive adhesive couldbe used on the back of the L clip to secure it to the fourth surface.Alternatively, solder could be applied directly to the coating on theedge or back of the mirror. In one embodiment, the solder could be usedas both the contact and as a conductive bus system.

One advantage of making external electrical contact to the third surfacematerial extended onto the edge of the substrate is that a conductivematerial is not longer required adjacent to the primary seal for filtermaterial on the first or second surface may be narrower while stillcovering the primary. Although a typical spectral filter material mayvary from 4 to 8 mm in width, it may be aesthetically pleasing to reducethis width below 4 mm. As the width of the primary seal is reduced, thewidth of the spectral filter material may also be reduced. Usingassembly and sealing techniques previously disclosed, it is possible toreduce the primary seal with to less than 1 mm which allows for aspectral filter width of less than 1 mm.

Another way to make electrical connection to the third surface, isolatedfrom the second surface is to use a conductive ink or epoxy to connectthe third surface to the edge. Thinning the conductive ink or epoxy andapplying it to the edge of the substrate contacts the third surface,without contacting the second surface. With this thinned conductiveepoxy, a conductive path can be applied such that contact is made on theedge or the back of the mirror element. An L clip may be applied contactand cured in place. A pressure sensitive adhesive may be used to securethe L clip in place during the curing process and to provide strainrelief with connecting wires.

If the corrosive effects of the environment on the metal can beminimized, very thin metal films or foils can used to establish a stableinterconnect to the conductive adhesive or bus. This metal foil or metalfilm on a plastic foil could be conformed to the shape of the J clip orother desired shape (without the need of expensive forming dies) andadhered to the substrate with an adhesive such as a pressure sensitive.This metal foil or metal film on plastic foil may be in the form of aroll of adhesive tape that is cut to size and applied to the EC elementsubstrate such that one end comes in contact with the conductive busthat is in contact with the front and/or back electrode(s). A spadeconnect or wire may be attached to the other end of the metal foil orfilm by traditional methods such as soldering or conductive adhesive, orthe end of the metal foil or tape may connect directly to the voltagesource for the EC element such as a printed circuit board.

At least one embodiment of a formable contact comprises of 0.001″palladium foil (Aldrich chemical Milwaukee, Wis.) laminated to 0.002″acrylic double side adhesive tape with a release liner (product 9495200MP series adhesive 3M Corporation, Minneapolis, Minn.). The metalfoil tape may be cut to an acceptable size for application on anelectrochromic device. The metal foil or metal film on plastic foil tapemay also be precut to a form or shape if desired.

At least one embodiment of a formable contact may be made from a plasticfilm and metallized with a metal such as gold, silver, titanium, nickel,stainless steel, tantalum, tungsten, molybdenum, zirconium, alloys ofthe above, or other metals or metal alloys that resist salt spraycorrosion. Also, palladium or other platinum group metals such asrhodium, iridium, ruthenium, or osmium may be used.

At least one embodiment of a formable contact uses a polymer carriercomprising of 0.002″ polyimide tape (#7648A42 McMasterCarr, Chicago,Ill.) coated with chrome and with any platinum group metal such asrhodium, indium, ruthenium, or osmium as the base, then coated with alayer of silver, gold or alloys thereof. This system is solderable andhas sufficient flexibility to wrap around the glass edge from onesubstrate surface to another surface.

At least one embodiment of a conductive coated polymer film is thoseproduced for the flexible circuit industry. In at least one embodiment,Sheldahl (Northfield, Minn.) produces combinations of polyimide (Kapton)and polyester films coated with ITO, Aluminum, copper, and gold.Polyimide tapes coated with a base metal may be plated or coated withdifferent metals or alloys to improve durability and/or solderability.These films can be coated with an adhesive or laminated to double sidedtape as described above. This metallized foil can be bent around a glassedge and maintain good conductivity.

At least one embodiment using a fibrous substrate is comprised of asolvent based ink placed onto a fiber backing. The conductive ink iscomprised of 10 parts methyl carbitol (Aldrich Milwaukee, Wis.), 2 partsBis A-epichlorhydrin copolymer (Aldrich Milwaukee, Wis.), and 88 partsof LCP1-19VS silver epoxy flake. The conductive ink may be applied tofibrous material such as those comprising of glass, metal, or cellulose.The system is heated sufficiently to evaporate the solvent. Theconductive and flexible formable contact is then applied to one surface,wrapping around to another surface.

At least one embodiment of a polymeric formable contact incorporates aconstruction mechanism to either protect the metal, hide the metalcolor, or offer another color more appealing to the outside appearanceof the glass edge. This construction would incorporate a polymeric filmon the outside, followed inwardly by the metal coating, and followedinwardly by an adhesive. The metal coating within the system would needto have an exposed edge for making contact to one of the glass insideconductive surfaces. Contact to this end could be made with an appliedconductive adhesive, solder, or other method to make a stable electricalcontact. The opposite end could have contact made with conductiveadhesive, solder, or other mechanical means.

In relation to the conductivity of a conductive polymer or composite,there are methods to describe the conductive polymer or composite'sconductivity. Those skilled in the art of Isotropic and anisotropicconductive adhesives commonly use a 4-pin probe for the resistancemeasurement. A common unit of measurement in the field of conductiveadhesives is ohms/square/mil. This measurement is expressed as not onlya factor of width, but also of thickness. This measurement, whenperformed on a nonconductive substrate, expresses the linearconductivity of a conductive polymer or composite such as a metal orcarbon or metal oxide conductive particle filled epoxy.

Another method by which to determine conductive polymer effectivenessfor use as a bus is to utilize isolated conductive pads and bridge theseisolated pads using the conductive polymer. A particular way to performthis test is to isolate conductive coatings on glass with laserablating, physical scoring, or chemical removal. The uncured conductivepolymer is applied to bridge the conductive pads so that the currentpath must pass through multiple contact interfaces, but is stillisolated from itself so as to not short the bridges together. Aresistance reading is taken at the ends, across the test piece.

Not all conductive polymers with high conductivity measured by theohm/sq/mil method have adequate interfacial electric contact to theelectrode surfaces used in an electrochromic device. Based on the abovecoupon using an ITO electrode as the isolated conductive pad, anacceptable resistance would be less than 1000 ohms. A more preferredresistance is less than 500 ohms, and an even more preferred resistanceis less than 200 ohms.

There are methods to affect this interfacial conductivity through theselection of conductive polymer components. The shape of the metalpowder or flake can affect the interfacial contact. Additives can alsoaffect the interfacial contact. Coupling agents, curing catalysts orcross linkers, epoxy resin systems, and methods by which to process thesilver epoxy can have an affect on the conductive polymer's ability tomake electrical contact to an adjacent conductive surface.

In at least one embodiment, a silver epoxy comprising of 3 partsHexahydrophthalic anhydride (Aldrich, Milwaukee Wis.), 2.14 partsAniline glycidyl ether (Pacific Epoxy Polymers), 0.1 parts Benzyldimethyl amine (Aldrich chemical, Milwaukee Wis.), and 23.9 parts silverflake LCP1-19VS (Ames Goldsmith, Glens Falls, N.Y.). When tested usingan ohm/square/mil conductivity measurement, results are acceptable(approximately 0.020 ohm/sq/mil).

In another embodiment, U.S. Pat. Nos. 6,344,157 and 6,583,201 disclosethe use of corrosion inhibitors, oxygen scavengers or metal chelatingagents for use in conductive adhesives.

In some cases, additives can be added to silver epoxies to stabilize orimprove conductivity. In at least one embodiment, a silver epoxycomprising of 3.4 parts Bis F epoxy resin (Dow Corporation; Midland,Mich.), 1.1 parts (Air Products and Chemicals; Allentown, Pa.), 20.5parts silver flake (Ames Goldsmith, Glens Falls, N.Y.), and 0.03 partsDiethanolamine (Aldrich Milwaukee, Wis.). Results are acceptable forboth conductivity (approximately 0.020 ohms/square/mil) and interfacialcontact (approximately 190 ohms).

As mentioned elsewhere in this patent, a sputtered or vacuum appliedmetal coating can be extended beyond the seal and over the edge of theglass to be used as an electrical connection. The metal coating shouldmeet the criteria of corrosion resistant metals listed above. Theelectrical connection to this coating could be made with a spring clip,or solder could be applied directly to the metal coating.

At least one embodiment of a solderable metal coating on glass, chromeis coated as the base layer then coated with any platinum group metalsuch as rhodium, iridium, palladium, ruthenium, or osmium, or copper,silver or gold, or alloys of the above are solderable using tin/leadsolders.

In another embodiment, chrome is coated as the base layer, then coatedwith any platinum group metal such as rhodium, iridium, palladium,ruthenium, or osmium, then coated with copper, silver or gold or alloysof the above are solderable using tin/lead solders.

In current automotive construction, restrictions exist using lead basecomponents such as solders. Other solders such as tin/zinc tin/silver,indium based solders containing silver, bismuth, tin, zinc, copper, andor antimony; silver solders or other non lead containing alloys may beused as a solder material. Soldering systems that may be employed areinductive heat, IR heat, ultrasonic, wave soldering or a soldering iron.

Another advantage to having a thinner conformable conductive bus clipmaterial as an electrical interconnect to the conductive epoxy is toreduce distortion in the reflection of the first substrate particularlywhen the first element is larger than the second element. Distortion canbe generated as a result of high temperature seal curing and differencesin the coefficients of thermal expansion between the seal and theconductive clips. The thicker the clip material, the more distortion isseen, particularly when using more flexible substrates. A thinner clipmaterial also has the advantage of being less noticeable if it is usedto wrap around the 3^(rd) surface to the back of the mirror. This isparticularly relevant if the first and second elements are aligned atthe point the clip wraps around. When the first element extends past thesecond element, the clip can be hidden entirely from view.

Example: An electrochromic mirror was made with flat 1.6 mm thick glassfor both front and rear elements. The front element was cut 0.040″larger (offset) on three sides. The inboard side (the side closest tothe driver) had no offset to facilitate easier filling and plugging ofthe part. A 0.001″×0.5″×0.75″ silver foil with 0.002″ thick pressuresensitive adhesive was applied on top and bottom of the second element.The conformable conductor contacted 0.010″-0.030″ of surface three thenrapped around to the fourth surface. A primary seal material was thendispensed around the perimeter of the first element leavingapproximately 0.040″ for an offset on three sides and an additional0.040 between the seal material and the edge of the glass element onboth the top and bottom edge of the second surface of the first element.The second element was then attached to the first element leaving a0.006″ space between the elements. The seal material was cured to fixthe elements in this spaced apart relationship. After cure of theprimary seal, a Conductive epoxy was then injected into the part fromthe edge on the top and bottom of the part, thereby encapsulating andmaking electrical contact with the third surface portion of theconformable conductor. It should be noted that this process ofdispensing a primary seal and a conductive seal could be accomplishedmore readily and easily on a dual dispense system, dispensing bothepoxies at the same time. The conductive epoxy was then cured. Themirror was inspected for distortion of the first surface reflection overthe conformable conductor, and no distortion was found. When similarmirrors were constructed using either Nickel, Stainless steel or Copperclips with a 0.003″ thickness, visual distortion can be seen near theperimeter of the first surface in the area directly above the clip.

As mentioned elsewhere herein, establishing electrical contact to thesecond and third surface conductive electrodes typically involvescoordination of a number of individually designed components. Turning toFIGS. 8 a-i, various options for electrical clips are depicted. Theplacement of the electrical clips is discussed throughout thisdisclosure in concert with the electrically conductive material. Apreferred electrically conductive material comprises 27.0 g Dow 354resin—a bis phenol F epoxy functional resin. Viscosity is preferably˜4000 cP 9.03 g Air Products Ancamine 2049—a cycloaliphatic amine cureagent. Viscosity preferably is ˜60 cP, 164 g Ames Goldsmith LCP 1-19VSsilver—a silver flake with tap density ˜3 g/cc and average particle size˜6 microns.

As described herein, at least one embodiment comprises a perimetermaterial surrounding the periphery of the element. A preferred perimetermaterial comprises 120 g Dymax 429 with some fillers added (i.e. 0.40 g6-24 silver flake available from Ames Goldsmith, 1.00 g silver coatedglass flake (i.e. Conduct-o-fil available from Potters industries), 12.0g crushed SK-5 glass filler available from Schott glass or a combinationthereof crushed into a powder and sieved with a 325 mesh). This materialcan be applied to the mirror edge using a number of techniques. Onetechnique is to load the material into a 30 cc syringe with a needle(˜18 gage). The needle can be oriented in a vertical position such thatthe perimeter material is dispensed with air pressure (<50 psi) onto theedge of the element while the element is being mechanically rotated on arobot arm or other mechanical device. The applied edge material can thenbe cured with UV light. Complete cure can be accomplished in 20 secondsor less. A robot may also be employed to rotate the part as it is beingcured to prevent sagging.

The intent of the perimeter material is to: protect the bus components;hide visible components like electrically conductive materials, clips,seals, glass edges; protect the cut edge of glass and offer an appealingvisual appearance of the mirror element. This may also be achieved withuse of conventional plastic bezels, grommets, elastomeric bezels and thelike.

Many different materials (such as epoxy, silicone, urethane, acrylate,rubber, hotmelt) and cure mechanisms can be used for this edgetreatment. The preferred cure method is by UV radiation. If fillers,dyes, or pigments that are partially opaque to UV radiation are used, acombination UV thermal cure can be used. Fillers such as glass orreflective silver aid the penetration of UV light by transmission,scattering or internal reflection, and are preferred for good depth ofcure. Preferably the perimeter material has a gray color or appearancesimilar to that of a ground glass edge or is dark or black in color.Colors may be varied by use of organic dyes, micas, impregnated micas,pigments, and other fillers. A darker, more charcoal appearance may beachieved by selecting different fillers and different amounts of filler.Less crushed glass will darken and flatten the color of the aboveformulation. Use of only crushed glass (or flakes or other glassparticle) with a different refractive index than the edge material resinbinder will give the appearance of a ground glass edge, or rough penciledge. Some additives are denser than the media they are contained in.Fumed silicas can be added to help prevent settling of the heaviercomponents (metal and glass particles); 2% by wt of fumed silica wasfound to be sufficient in the preferred method.

Other ways to apply the perimeter material to the element edge includeapplying the material with a roll, wheel, brush, doctor bar or shapedtrowel, spraying or printing.

The perimeter edge materials chosen for a vehicular exterior applicationpreferably meet the following test criteria, these criteria simulate theexterior environment associated with a typical motor vehicle: UVstability (2500 kJ in UV weatherometer)—no yellowing or cracking orcrazing of material when exposed to direct UV; Heat resistance—little orno color change, no loss of adhesion; Humidity resistance—little or nocolor change, no loss of adhesion; Thermal-cycling—No loss of adhesion,no cracking; CASS or salt spray—protection of the underlying metalcoatings and conductive epoxy systems; No loss of adhesion and novisible sign of underlying corrosion and High Pressure water test—noloss of adhesion after parts have been tested in previous statedtesting.

The perimeter edge materials chosen for an automotive exteriorapplication preferably meet the following test criteria. These criteriasimulate the exterior environment associated with a typical vehicle: UVstability (2500 kJ in UV weatherometer)—no yellowing or cracking orcrazing of material when exposed to direct UV; Heat resistance—little orno color change, no loss of adhesion; Humidity resistance—little or nocolor change, no loss of adhesion; Thermal-cycling—No loss of adhesion,no cracking; CASS or salt spray—protection of the underlying metalcoatings and conductive epoxy systems; No loss of adhesion and novisible sign of underlying corrosion and High Pressure water test—noloss of adhesion after parts have been tested in previous statedtesting.

With further reference to FIGS. 7 a-n, various embodiments forconfiguration of second and third surface electrode contact are shown.FIG. 7 a-n depict configurations similar to that discussed elsewhereherein having a first surface stack of materials, a second surface stackof materials, a third surface stack of materials and, or, a fourthsurface stack of materials. The word stack is used herein to refer tomaterials placed proximate a given surface of a substrate. It should beunderstood that any of the materials as disclosed in commonly assignedU.S. Pat. Nos. 6,111,684, 6,166,848, 6,356,376, 6,441,943, Ser. No.10/115,860 U.S. Pat. Nos. 5,825,527, 6,111,683, 6,193,378, Ser. Nos.09/602,919, 10/260,741 and 10/430,885, the disclosures of which areincorporated herein by reference, may be employed to define a unitarysurface coating, such as a hydrophilic coating. Preferably, second,third and fourth surface stacks are as disclosed herein or in commonlyassigned U.S. Pat. Nos. 5,818,625, 6,111,684, 6,166,848, 6,356,376,6441,943 and 6,700,692, the disclosure of each is incorporated in itsentirety herein by reference.

FIGS. 7 d-i depicts various embodiments for configuration of the anodeand cathode connections to the second and third surface conductiveelectrodes, respectively. Preferably, the sheet resistance of the thirdsurface conductive electrode is less than that of the second surfaceconductive electrode. Therefore, the cathode contact area may besubstantially less than the anode contact area. It should be understoodthat in certain embodiments, the anode and cathode connections may bereversed.

The configuration of FIG. 7 j may be used to constructing a no, ornarrow, bezel rearview mirror assembly that does not incorporate aspectral filter. If the perimeter seal and electrode contact means 748 j1, 748 j 2 were both substantially moved to the mirror edge there is nota requirement for a spectral filter material to cover the seal/contactarea. When this approach to mirror element construction is used, themirror element darkens substantially completely to the perimeter edgeduring glare conditions. In this approach most or all of the seal andcontact area can be substantially moved from the perimeter of mirrorsubstrate one, surface two and substrate two, surface three, to theedges of substrate one and substrate two.

In at least one embodiment, the top edge of the first substrate and thebottom edge of the second substrate were coated with a conductive epoxyto transfer electrically conductivity from the conductive electrode oneach substrate to the substrate edge. The conductive epoxy is preferablyformulated using: 3.36 g D.E.R. 354 epoxy resin (Dow Chemical, Midland,Mich.), 1.12 g Ancamine 2049 (Air Products and Chemicals, Reading Pa.)and 20.5 g of silver flake with an average particle size of 7 um tapdensity of 3.0-4.0 g/cc was thoroughly mixed into a uniform paste. Thisconductive epoxy mixture was thinned with enough toluene to produce alow viscosity conductive paint that could easily be applied to thesubstrate edge. The coated substrates were put in a 60 C oven for 15 to20 minutes to evaporate the toluene.

A uniform layer of an epoxy that was sparsely filled with conductiveparticles (Z-axis conductor) was applied to 0.001″ thick copper foil.The Z axis epoxy (5JS69E) was formulated as follows: 18 g of D.E.N. 438,2 g D.E.N. 431 (Dow Chemical, Midland, Mich.), 1.6 g of US-206 fumedsilica (Degussa Corporation, Dublin, Ohio), 6.86 g Ancamine 2049 and10.0 g silver flake FS 28 (Johnson Matthey, Royston, Hertfordshire, UK)was blended into a uniform paste. The silver flake filler had a tapdensity of 2.3 g/cc and an average particle size of 23 um. A cured thinfilm of this epoxy formulation becomes conductive in the z-axis and notin the x or y axis. This z-axis conductive epoxy was thinned with enoughtoluene or THF solvent to produce a viscosity suitable to spread into athin uniform thickness onto the copper foil. The solvent was thenevaporated off in a 60 c oven for approximately 5 min. The epoxyremained slightly tacky after solvent evaporation. The edges of the twosubstrates were aligned with virtually no offset. The gap between thesubstrates was accurately maintained by using precision sized PMMA beadsas spacers. A small piece of Kapton tape approximately 2 mm wide wasused on one end extending across the edges of both substrates and thecell spacing. The Kapton tape would eventually be removed from the cellafter assembly and the Kapton tape area, which was not wetted withepoxy, would be used as a fill port. The copper foil with the z-axisconductive epoxy was then applied to the peripheral edge of the partsuch that the epoxy wetted both substrate edges completely. The elementwas then cured in an oven at 200 C for 15 minutes. After the cure, asmall separation was made in the copper foil on each side toelectrically isolate the copper foil on the top from the copper foil onthe bottom of the part. The copper foil covering the Kapton tape and theKapton tape was removed. The opening created by the removed Kapton tapewas used to fill the part. The opening was then plugged with an UVcurable adhesive. The opening on the opposite side was also plugged withan UV curable adhesive but before filling.

FIGS. 8 a-n depict various embodiments for configuration of anelectrical clip. Generally, the individual clips are depicted to definesubstantially a “J” shaped cross section.

The embodiment of FIG. 8 a depicts a J-clip 884 a configured toaccommodate an electrical connection post (not shown) fixed thereto. Inat least one embodiment, the first and second electrical clips areconfigured in combination with a carrier plate (as described in detailherein with respect to FIGS. 10 a-c) to form a “plug” type electricalconnector. The J-clip comprises an edge portion 883 a and an innerelement portion 882 a. The inner element portion is configured to bepositioned between a first and second substrate and to be in electricalcontact with an electrically conductive epoxy, solder or conductiveadhesive to make electrical contact with either a second or thirdsurface stack of materials.

FIG. 8 b depicts a series of apertures 885 b extending through an innerelement portion 882 b to, at least in part, facilitate a mechanical and,or, electrical contact with an electrically conductive material. TheJ-clip 884 b comprises a wire connection feature 886 b and an edgeportion 883 b. The wire connection feature may be configured to eitheraccommodate a solder or a crimp type wire connection.

FIGS. 8 c-e depict various J-clip configurations 884 c, 884 d, 884 ecomprising an electrical connection stab 886 c, 886 d, 886 e having afriction fit hole 887 c, 887 d, 887 e. Each J-clip has an edge portion883 c, 883 d, 883 e and an inner element portion 882 c, 882 d, 882 e.FIG. 8 c depicts having a portion 885 c of the J-clip folded such thatthe J-clip is not as long and is taller than the J-clip of FIG. 8 d.FIG. 8 e depicts a series of apertures 881 e extending through a thirdportion of the clip to provide a stress relief area to accommodatevariations in material coefficients of expansion.

FIG. 8 f depicts a raised portion 885 f on a J-clip 884 f along with awire crimp 886 f configured to spatially separate the wire contact areafrom the element. This J-clip comprises an edge portion 883 f and aninner element portion 882 f.

FIG. 8 g depicts a J-clip 884 g comprising a wire crimp 886 g, an edgeportion 883 g and an inner element portion 882 g. FIG. 8 h depicts aJ-clip 884 h comprising a wire crimp 886 h, an edge portion 883 h and aninner element portion 882 h. The inner element portion comprises aseries of apertures 881 h to facilitate enhanced mechanical and, or,electrical contact. FIG. 8 i depicts a J-clip 884 i comprising a wirecrimp 886 i, an edge portion 883 i and an inner element portion 882 i.FIG. 8 j depicts a J-clip 884 j comprising a wire crimp 886 j, an edgeportion 883 j and an inner element portion 882 j.

FIG. 8 k depicts a J-clip 884 k similar to that of FIG. 8 a excepthaving a longer portion for adhering to a substrate. This J-clipcomprises an edge portion 883 k and an inner element portion 882 k.

FIG. 8 l depicts a J-clip 884 l having two large apertures 886 l forstress relief along with four bumps 887 l for enhancing electricalconnection placement. This J-clip comprises an edge portion 883 l and aninner element portion 882 l.

FIG. 8 m depicts a J-clip 884 m comprising a wire crimp 886 m, an edgeportion 883 m and an inner element portion 882 m. FIG. 8 n depicts aJ-clip 884 n comprising a wire crimp 886 n, an edge portion 883 n and aninner element portion 882 n.

Electro-optic mirrors often incorporate a bezel that covers the edge ofthe mirror element and the electrical bus connections. In addition, themirror edge and bus connection are often encapsulated in a pottingmaterial or sealant. As long as the mirror remains functional, theaesthetics of the mirror edge and bus connection are not a concern. Incontrast, Electro-optic mirrors without a bezel typically have both themirror element edge and the associated electrical bus connectionsexposed to the environment. The bus connection typically utilizes ametal member (the term metal throughout this discussion on corrosion canrepresent a pure metal or a metal alloy) such as a formed clip or strip.Electro-optic mirrors with bezels often have formed metallic clips orstrips made of copper or copper alloy. The appearance and corrosionresistance of these formed clips or strips becomes important if goodaesthetics are to be maintained over the life of the vehicle. Copper andcopper alloys tend to corrode and turn green in the salty wetenvironments an EC outside mirror is exposed to. This is notaesthetically acceptable. Even if the metal bus cannot be vieweddirectly, the formed metal clips or strips are typically made of thinmaterial, usually less than 0.010″ thick and more typically 0.005″ orless in thickness. These thin metal pieces can corrode quickly resultingin structural failure, loss of spring electrical contact force or lossof electrical continuity. This issue can be minimized if the edge of themirror and/or back of the mirror is covered with a paint or coating. Themetal clip could also be protected from the environment with a coatingsuch as a conformal coating, paint or varnish or metal plating orcladding. Examples of suitable conformal coatings are:

-   -   1. UV curing epoxy system comprising of 354 bis F resin (Dow        Chemical) with 2% (by weight) of US-206 (Degussa) and 3% (by        weight) of UVI-6992 (Union Carbide Corp—subsidiary of Dow        Chemical). 0-3% (by weight) of US-206 and 2-5% (by weight) of        UVI-6992.    -   2. Solvated urethane conformal coating like Humiseal 1A33 (Chase        Corporation, Woodside N.Y.)    -   3. Solvated polyisobutylene comprising of 3 parts (by weight)        pentane and 1 part (by weight)

Vistanex LM-MS-LC (Exxon Chemical)

Examples of protective metal platings include gold, palladium, rhodium,ruthenium, nickel and silver. In general these coatings or surfaceplatings retard the corrosion and extend the useful life of theelectrical bus; however, corrosion often eventually occurs. Anotherapproach to extending useful bus life is to make the bus clip or stripout of a metal or metal alloy that has good corrosion resistance insalty environments. Suitable metals include the noble metals and noblemetals alloys comprising gold, platinum, iridium, rhodium, ruthenium,palladium and silver as well as metals and metal alloys of titanium,nickel, chromium, molybdenum, tungsten and tantalum including stainlesssteel, Hastalloy C, titanium/aluminum alloys, titanium palladium alloys,titanium ruthenium alloys. Zirconium and its alloys also perform wellunder certain circumstances. A table ranking a number these metals andmetal alloys after copper accelerated salt spray (CASS) testing isincluded herein. The rankings are 4—unacceptable corrosion, 3—corrosionevident but acceptable, 2—light corrosion evident, 1—very light/nocorrosion.

Corrosion Ranking Table Material Plating Ranking Olin 725 (Cu—Ni—Sn)None 4 Olin 638 (Cu—Al—Si—Co) None 4 Olin 194 (Cu—Fe—P—Zn) None 4 Olin510 Phos. Bronze (Cu—Sn—P) None 4 Olin 713 None 4 Phos. Bronze Tin 4Olin 770 German Silver (Cu—Zn—Ni) None 3 Olin 752 (Cu—Zn—Ni) None 3Monel (Ni—Cu) None 3 Brush Wellman (Cu—Be) None 4 174-10 Palladium 3174-10 Silver 3 174-10 Tin 4 302 Stainless Steel None 2 302 StainlessSteel Tin 3 302 Stainless Steel Silver 3 302 Stainless Steel Rhodium 2302 Stainless Steel Nickel Strike 1 302 Stainless Steel PassivatedSurface by 2 JS 316 Stainless Steel None 2 Tin Foil None 3 Silver FoilNone 1 Nickel None 1 Titanium Unalloyed (grade 1) None 1 TitaniumUnalloyed (grade 2) None 1 Titanium Unalloyed (grade 4) None 1 Ti—6Al—4V(grade 5) None 1 Ti—3Al—2.5V (grade 9) None 1 Ti—0.15—Pd (grade 11) None1 Ti—0.15Pd (grade 16) None 1 Ti—0.1Ru (grade 26) None 1Ti—3Al—2.5V—0.1Ru (grade 28) None 1 Ti—6Al—4V—0.1Ru (grade 29) None 1Molybdenum Foil None 2 Gold Foil None 1 Rhodium Foil None 1 Lead FoilNone 3 Tungsten Foil None 1 Palladium Foil None 1 Cobalt Foil None 4Tantalum Foil None 1 Nickel Foil None 1 Nickel Foil Silver 1 316Stainless Steel Tin 3

When the bus interconnection technique incorporates the use of two ormore different metals in close contact with one another, the effects ofgalvanic corrosion is preferably considered. Many interconnectiontechniques utilize conductive adhesives. These adhesives generally areorganic resins such as epoxy, urethane, phenolic, acrylic, silicone orthe like that are embedded with conductive particles such as gold,palladium, nickel, silver, copper, graphite or the like. Unlike a metalsolder joint, organic resins breathe. Moisture, oxygen and other gassescan diffuse through organic resins and cause corrosion. When dissimilarmetals are in contact with one another this corrosion may be acceleratedby the difference in the electrochemical potential of the metals.Generally, the greater the difference in electrochemical potentialbetween the metal, the greater the probability of galvanic corrosion. Itis therefore desirable to minimize the difference in electrochemicalpotential between metals selected for use in a bus system, especiallywhen a naturally non-hermetic electrically conductive adhesive is used.When one or both of the metals are plated, it is preferred that aplating material is selected that has an electrochemical potential inbetween the electrochemical potentials of the two metals. For officeenvironments that are humidity and temperature controlled theelectrochemical potentials differences between the metals are preferablyno more than 0.5V. For normal environments the potential difference ispreferably no more than 0.25V. For harsh environments the potentialdifference is preferably no more than 0.15V. Many conductive adhesivesuse silver particulate or flake as the conductive filler. Silverrepresents a good compromise between cost and nobility. Silver is alsohas excellent conductivity. As described in metals galvaniccompatibility charts such as those supplied by Engineers Edge(www.engineersedge.com) and Laird Technologies (www.lairdtech.com),silver has an anodic index of 0.15V. Tin plated copper or copper alloythat is typically used for bus connections in bezeled mirrors has ananodic index of 0.65V. When tin plated copper is used in contact withsilver, the large 0.5V anodic potential difference is acceptable for usein controlled office like environments. The environment associated withoutside vehicular mirrors is by no means a controlled environment. Apotential difference of less than 0.45V is desirable, a difference ofless than 0.25V is preferred and a difference of less than 0.15V is mostpreferred.

Metals Galvanic Compatibility Chart Anodic Metal Surface Index Gold,solid and plated, Gold-platinum alloy, Graphite Carbon 0.00 Rhodiumplated on silver 0.05 Rhodium plating 0.10 Silver, solid or plated; Highsilver alloys, monel metal. High nickel-copper 0.15 alloys Nickel, solidor plated, titanium and s alloys, Monel, nickel-copper alloys, 0.30titanium alloys Copper, beryllium copper, cooper; Ni—Cr alloys;austenitic corrosion-resistant 0.35 steels; most chrome-poly steels;specialty high-temp stainless steels, solid or plated; low brasses orbronzes; silver solder; German silvery high copper- nickel alloys;nickel-chromium alloys Commercial yellow brass and bronzes 0.40 Highbrasses and bronzes, naval brass, Muntz metal 0.45 18% chromium typecorrosion-resistant steels, common 300 series stainless 0.50 steelsChromium plated; tin plated; 12% chromium type corrosion-resistantsteels; 0.60 Most 400 series stainless steels Tin-plate; tin-lead solder0.65 Lead, solid or plated, high lead alloys 0.70 Aluminum, wroughtalloys of the 2000 Series 0.75 Iron, wrought gray or malleable, plaincarbon and low alloy steels; armco iron; 0.85 cold-rolled steelAluminum, wrought alloys other than the 2000 Series aluminum, castalloys of 0.90 the silicon type; 6000 Series Aluminum Aluminum, castalloys other than silicon type, cadmium, plated and chromate 0.95Hot-dip zinc plate; galvanized steel or electro galvanized steel 1.20Zinc, wrought; zinc-base die-casting alloys; zinc plated 1.25 Magnesium& magnesium-base alloys, cast or wrought 1.75 Beryllium 1.85 Highbrasses and bronzes, naval brass, Muntz metal 0.45 18% chromium typecorrosion-resistant steels, common 300 series stainless 0.50 steelsIt should be noted that the potential differences between metalsdepends, at least in part, on the nature of the corrosive environmentthey are measured in. Results measured in, for example, seawater may beslightly different than for fresh water. It should also be noted thatthere can be large differences between passive and active surfaces ofthe same material. The anodic potential of a stainless steel surface maybe substantially reduced by a passivation treatment using nitric acidand/or solutions of oxidizing salts. The anodic potential difference maybe kept within the most preferred 0.15V if silver is used in combinationwith, for example, gold, gold/platinum alloys, platinum, zirconium,carbon graphite, rhodium, nickel, nickel-copper alloys, titanium andmonel. The potential difference may be kept within the preferred 0.25Vwith for example beryllium copper, brass, bronze, silver solder, copper,copper-nickel alloys, nickel-chrome alloys, austenitic corrosionresistant steels, most chrome-moly steels. The potential difference maybe kept within the desired 0.40V by using, for example, 18-8 stainlesssteel or 300 series stainless steels, high brasses and bronzes, navalbrass and Muntz metal. When a plating is used, it is desirable to havethe plating material within these anodic potential ranges and mostpreferably have a potential between the two base materials in closecontact with each other. For example, gold, palladium, rhodium,ruthenium, nickel or silver plating generally meets these requirements.The electrical bus is generally connected to the EC mirror drive voltagesource by use of a spade connector or soldered joint. When a solderedjoint, or connection, is used, the bus metal is preferably solderable.Platings such as gold, palladium, rhodium, ruthenium, nickel, silver andtin can enhance the solderability of the bus clip. For instance, eventhough tin is not a preferred plating, a tin plated stainless steel busclip solders easily when compared to a plain stainless steel clip. Asolder friendly more preferred substrate/plating combination isstainless steel with palladium, silver, nickel or rhodium plating.Stainless steel with a nickel plating followed by a silver, palladium,gold, rhodium or ruthenium plating is a preferred material. Otherpreferred materials include metals or metal alloys comprising tantalum,zirconium, tungsten, and molybdenum with a nickel, silver, gold,palladium, rhodium and ruthenium plating. Other preferred materials aremetals, or metal alloys, comprising titanium or nickel with a nickeland/or silver plating. For enhanced stability, it is desirable topassivate the surface of the base metal.

Turning now to FIGS. 9 a and 9 b, a mirror element comprising a firstsubstrate 912 b and a second substrate 902 b is depicted subsequent tobeing received by a carrier assembly. The carrier assembly comprises asubstantially rigid portion 901 a, 901 b integrated with a pliableperipheral gripping portion 903 a, 903 b. The substantially rigidportion and the pliable peripheral gripping portion may be co-molded,individually molded and adhered to one another, designed to friction fittogether, designed to interference fit together, individually molded andmelted together, or a combination thereof. In any event, the pliableperipheral gripping portion 903 a, 903 b is preferably designed toresult in an interface 909 between the pliable peripheral grippingportion and the perimeter material beyond the crown 913 such that fromnear the crown to near the tip 907 there is a restraining forcegenerated that, at least in part, retains the element proximate thecarrier assembly as desired. An additional adhesion material 905 a, 905b may be utilized to further retain the element proximate the carrierassembly. It should be understood that the perimeter portion 903 a, 903b may be constructed, at least in part, from a material that adheres tothe perimeter material 960 such that the retentive force is alsogenerated along the interface 911 on the rigid portion 901 a, 901 b sideof the crown 903 a, 903 b; in such a case, the perimeter portion 903 a,903 b may extend short of the crown or just beyond the crown as depictedin FIG. 9 b. Preferably, the perimeter portion tip 907 is taperedslightly to provide a visually appealing transition to the elementirrespective of whether the perimeter portion extends beyond the crown.It should be understood that the shape of the perimeter material may bealtered to provide at least one edge substantially parallel to surface915 and the perimeter portion may be designed to impart a morepronounced transition between the crown and the interface 909.

FIG. 9 c depicts an element comprising a first substrate 912 c and asecond substrate 902 c positioned within a carrier 901 c and perimeterportion 903 c. This configuration typically represents the as-moldedcondition of the pliable peripheral gripping portion. FIG. 9 b wouldtypically represent the installed position of the pliable peripheralgripping portion. The installed position allows the pliable peripheralgripping portion to conform to the potential irregularities of the glassprofile. FIG. 9 b is depicting a mechanical interlock between the rigidportion of the carrier and the pliable peripheral gripping portion. Thisis useful for materials that are not intended to be bonded togetherwhether adhered or bonded through a molding process. The mechanicalinterlocks can be spaced around the perimeter of the assembly as needed.FIG. 9 c is depicting a cross section without a mechanical interlock.Both sections can be used as needed. Another difference between FIGS. 9b and 9 c is the height of the pliable peripheral gripping portion offof the back side of the carrier. FIG. 9 b limits the height off of theback of the carrier of the pliable peripheral gripping portion byplacing some of the pliable peripheral gripping portion between theglass and carrier in place of the heater/foam assembly. This potentiallyeliminates clash conditions inside the housing. FIG. 9 c can be used toallow the heater/foam assembly to be placed to the edge of the glassperimeter. This allows heating of the glass assembly all the way out tothe edge. However, it could potentially create clash conditions of themirror assembly in the mirror housing.

Turning now to FIGS. 9 d-m, various carrier plates are depicted withperimeter gripping portions. FIGS. 9 d-g depict a carrier plate 901 d,901 e, 901 f, 901 g having an integral perimeter gripping portion 903 d,903 e, 903 f, 903 g. In at least one embodiment, the perimeter grippingportion comprises a “goose neck” cross section shape and comprises aseries of alternating lands 903 d 1, 903 e 1, 903 f 1 and apertures 903d 2, 903 e 2, 903 g 2. The combination of the goose neck shape and thealternating lands and apertures provides hoop stress relief to accountfor differences in expansion coefficients between the element and thecarrier plate/perimeter gripping portion.

FIG. 9 h depicts an element comprising a first substrate 912 h and asecond substrate 902 h held in spaced apart relationship with respect toone another via a primary seal material 978 h within a carrier plate 901h and perimeter gripping portion 903 h. In this embodiment, theperimeter gripping portion comprises a compressible material that issandwiched between the element and an outer part of the carrier plate toallow for the variations in expansion coefficients between the elementand the carrier plate/perimeter gripping portion.

FIG. 9 i depicts an element comprising a first substrate 912 i and asecond substrate 902 i held in spaced apart relationship with respect toone another via a primary seal material 978 i within a carrier plate 901i and perimeter gripping portion 903 i. In this embodiment, theperimeter gripping portion comprises a compressible material 904 i thatis sandwiched between the carrier plate and the perimeter grippingportion to allow for the variations in expansion coefficients betweenthe element and the carrier plate/perimeter gripping portion.

FIG. 9 j depicts a carrier plate 901 j having a swivel portion 901 j 1for pivotally attaching a perimeter gripping portion 903 j. The factthat the perimeter gripping portion is allowed to pivot about the swivelportion accounts for variations in expansion coefficients between theelement and the carrier plate/perimeter gripping portion.

FIG. 9 k depicts a carrier plate 901 k having a perimeter grippingportion 903 k. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). Acompression material 904 k is provided to account for variations inexpansion coefficients between the element and the carrierplate/perimeter gripping portion.

FIG. 9 l depicts a carrier plate 901 l having a perimeter grippingportion 903 l. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). A series ofvertically extending compression elements 904 l are provided to accountfor variations in expansion coefficients between the element and thecarrier plate/perimeter gripping portion.

FIG. 9 m depicts a carrier plate 901 m having a perimeter grippingportion 903 m. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). A series ofhorizontally extending compression elements 904 m are provided toaccount for variations in expansion coefficients between the element andthe carrier plate/perimeter gripping portion.

Turning now to FIGS. 10 a-c, an element 1012 a is depicted proximate analignment plate 1001 a, 1001 b and an electrical circuit board 1020 a,1020 b. In at least one embodiment, an electrical clip 1084 a, 1084 bhaving a contact post 1086 a, 1086 c is connected to an elementelectrical connection 1085 a, 1085 b. The element electrical connectionmay be via an electrically conductive epoxy, solder, conductive adhesiveor an edge spring clip. When the element is engaged with the electricalcircuit board the contact post is received through a hole 1021 a, 1021 cin the electrical circuit board and is slidingly engaged with frictionfit contacts 1022 a, 1022 c, 1023 a, 1023 c. FIG. 10 c depicts anenlarged view of the corresponding area 1027 b of FIG. 10 b. In at leastone embodiment, the alignment plate comprises apertures 1003 a, 1004 afor alignment with apertures 1024 b, 1025 b, respectively, of theelectrical circuit board. Preferably, alignment pins (not shown) areprovided elsewhere in the associated mirror assembly, such as, in thehousing or bezel to accurately position the individual components withinthe assembly. In at least one embodiment, the alignment plate comprisesan aperture 1002 a through which the contact post is received foralignment with the corresponding hole in the circuit board. In at leastone embodiment, the alignment plate comprises features 1005 a, 1005 b,1006 a, 1006 b for accurately securing the components within a completeassembly. It should be understood that the electrical circuit board maycomprise components such as a microprocessor and, or, other electricalcomponents, such as a display driver, a compass sensor, a temperaturesensor, a moisture detection system, an exterior light control systemand operator interfaces that are at least partially shared with at leastone mirror element dimming circuitry.

It should be understood that the above description and the accompanyingfigures are for illustrative purposes and should in no way be construedas limiting the invention to the particular embodiments shown anddescribed. The appending claims shall be construed to include allequivalents within the scope of the doctrine of equivalents andapplicable patent laws and rules.

1. A variable reflectance mirror assembly, comprising: a firstsubstantially transparent substrate having first and second surfaces,the first substrate including a substantially transparent layer ofmaterial on at least a portion of the second surface; a second substratehaving third and fourth surfaces, the second substrate including atleast one at least partially reflective layer on at least a portion ofthe third surface; a first electrical contact electrically connected tosaid substantially transparent layer of material; a second electricalcontact electrically connected to said at least one at least partiallyreflective layer; an electrochromic material positioned between saidfirst substantially transparent substrate and said second substrate, theelectrochromic material having a light transmittance that is variable asa function of voltage applied between the first and second electricalcontacts; and an electrical circuit configured to insure that said firstelectrical contact is maintained as an anode and said second electricalcontact is maintained as a cathode.
 2. The assembly as in claim 1further including at least two materials interposed and providing anelectrical connection between the first electrical contact and thesubstantially transparent layer of material, wherein a difference ofelectrochemical potentials between the two materials is less than 0.45V.3. The assembly as in claim 1 further including at least two materialsinterposed and providing an electrical connection between the firstelectrical contact and the substantially transparent layer of material,wherein a difference of electrochemical potentials between the twomaterials is less than 0.25 V.
 4. The assembly as in claim 1 furtherincluding at least two materials interposed and providing an electricalconnection between the first electrical contact and the substantiallytransparent layer of material, wherein a difference of electrochemicalpotentials between the two materials is less than 0.15V.
 5. The assemblyas in claim 1 further including at least two materials interposed andproviding an electrical connection between the second electrical contactand the at least one at least partially reflective layer, wherein adifference of electrochemical potentials between the two materials isless than 0.45 V.
 6. The assembly as in claim 1 further including atleast two materials interposed and providing an electrical connectionbetween the second electrical contact and the at least one at leastpartially reflective layer, wherein a difference of electrochemicalpotentials between the two materials is less than 0.25 V.
 7. Theassembly as in claim 1 further including at least two materialsinterposed and providing an electrical connection between the secondelectrical contact and the at least one at least partially reflectivelayer, wherein a difference of electrochemical potentials between thetwo materials is less than 0.15 V.
 8. The assembly as in claim 1 whereinsaid first electrical contact comprises at least one metal selected fromthe group consisting of gold, platinum, iridium, rhodium, ruthenium,palladium, silver titanium, nickel, chromium, molybdenum, tungsten,tantalum, stainless steel, Hastalloy C, titanium/aluminum alloys,titanium palladium alloys, titanium ruthenium, Zirconium and alloysthereof.
 9. A variable reflectance mirror element as in claim 1 whereinan electrical connection between said first electrical contact and saidsubstantially transparent layer of material has a resistance of lessthan 1000 Ohms.
 10. A variable reflectance mirror element as in claim 1wherein an electrical connection between said first electrical contactand said substantially transparent layer of material has a resistance ofless than 500 Ohms.
 11. A variable reflectance mirror element as inclaim 1 wherein an electrical connection between said first electricalcontact and said substantially transparent layer of material has aresistance of less than 200 Ohms.
 12. A variable reflectance mirrorelement as in claim 1 wherein an electrical connection between saidsecond electrical contact and said at least one at least partiallyreflective layer has a resistance of less than 1000 Ohms.
 13. A variablereflectance mirror element as in claim 1 wherein an electricalconnection between said second electrical contact and said at least oneat least partially reflective layer has a resistance of less than 500Ohms.
 14. A variable reflectance mirror element as in claim 1 wherein anelectrical connection between said second electrical contact and said atleast one at least partially reflective layer has a resistance of lessthan 200 Ohms.